diff --git a/Packages/VRM10/Runtime/IO/Vrm10Exporter.cs b/Packages/VRM10/Runtime/IO/Vrm10Exporter.cs
index fc6724f5d..e285ec744 100644
--- a/Packages/VRM10/Runtime/IO/Vrm10Exporter.cs
+++ b/Packages/VRM10/Runtime/IO/Vrm10Exporter.cs
@@ -14,6 +14,7 @@ namespace UniVRM10
         public const string SPRINGBONE_EXTENDED_COLLIDER_SPEC_VERSION = "1.0";
         public const string NODE_CONSTRAINT_SPEC_VERSION = "1.0";
         public const string MTOON_SPEC_VERSION = "1.0";
+        public const string VRMC_springBone_limit_SPEC_VERSION = "1.0-draft";
 
         public const string LICENSE_URL_JA = "https://vrm.dev/licenses/1.0/";
         public const string LICENSE_URL_EN = "https://vrm.dev/licenses/1.0/en/";
@@ -451,63 +452,70 @@ namespace UniVRM10
                 GravityPower = y.m_gravityPower,
             };
 
-            switch (y.m_anglelimitType)
+            if (y.transform.childCount > 0)
             {
-                case UniGLTF.SpringBoneJobs.AnglelimitTypes.Cone:
-                    {
-                        var limit = new UniGLTF.Extensions.VRMC_springBone_limit.VRMC_springBone_limit
+                // childが存在する => 末端でない
+                switch (y.m_anglelimitType)
+                {
+                    case UniGLTF.SpringBoneJobs.AnglelimitTypes.Cone:
                         {
-                            Limit = new UniGLTF.Extensions.VRMC_springBone_limit.Limit
+                            var limit = new UniGLTF.Extensions.VRMC_springBone_limit.VRMC_springBone_limit
                             {
-                                Cone = new UniGLTF.Extensions.VRMC_springBone_limit.ConeLimit
+                                SpecVersion = VRMC_springBone_limit_SPEC_VERSION,
+                                Limit = new UniGLTF.Extensions.VRMC_springBone_limit.Limit
                                 {
-                                    Rotation = ReverseXToFloat4(y.m_limitSpaceOffset),
-                                    Angle = y.m_pitch,
+                                    Cone = new UniGLTF.Extensions.VRMC_springBone_limit.ConeLimit
+                                    {
+                                        Rotation = ReverseXToFloat4(y.m_limitSpaceOffset),
+                                        Angle = y.m_pitch,
+                                    }
                                 }
-                            }
-                        };
-                        glTFExtension extensions = default;
-                        UniGLTF.Extensions.VRMC_springBone_limit.GltfSerializer.SerializeTo(ref extensions, limit);
-                        joint.Extensions = extensions;
-                        break;
-                    }
-                case UniGLTF.SpringBoneJobs.AnglelimitTypes.Hinge:
-                    {
-                        var limit = new UniGLTF.Extensions.VRMC_springBone_limit.VRMC_springBone_limit
+                            };
+                            glTFExtension extensions = default;
+                            UniGLTF.Extensions.VRMC_springBone_limit.GltfSerializer.SerializeTo(ref extensions, limit);
+                            joint.Extensions = extensions;
+                            break;
+                        }
+                    case UniGLTF.SpringBoneJobs.AnglelimitTypes.Hinge:
                         {
-                            Limit = new UniGLTF.Extensions.VRMC_springBone_limit.Limit
+                            var limit = new UniGLTF.Extensions.VRMC_springBone_limit.VRMC_springBone_limit
                             {
-                                Hinge = new UniGLTF.Extensions.VRMC_springBone_limit.HingeLimit
+                                SpecVersion = VRMC_springBone_limit_SPEC_VERSION,
+                                Limit = new UniGLTF.Extensions.VRMC_springBone_limit.Limit
                                 {
-                                    Rotation = ReverseXToFloat4(y.m_limitSpaceOffset),
-                                    Angle = y.m_pitch,
+                                    Hinge = new UniGLTF.Extensions.VRMC_springBone_limit.HingeLimit
+                                    {
+                                        Rotation = ReverseXToFloat4(y.m_limitSpaceOffset),
+                                        Angle = y.m_pitch,
+                                    }
                                 }
-                            }
-                        };
-                        glTFExtension extensions = default;
-                        UniGLTF.Extensions.VRMC_springBone_limit.GltfSerializer.SerializeTo(ref extensions, limit);
-                        joint.Extensions = extensions;
-                        break;
-                    }
-                case UniGLTF.SpringBoneJobs.AnglelimitTypes.Spherical:
-                    {
-                        var limit = new UniGLTF.Extensions.VRMC_springBone_limit.VRMC_springBone_limit
+                            };
+                            glTFExtension extensions = default;
+                            UniGLTF.Extensions.VRMC_springBone_limit.GltfSerializer.SerializeTo(ref extensions, limit);
+                            joint.Extensions = extensions;
+                            break;
+                        }
+                    case UniGLTF.SpringBoneJobs.AnglelimitTypes.Spherical:
                         {
-                            Limit = new UniGLTF.Extensions.VRMC_springBone_limit.Limit
+                            var limit = new UniGLTF.Extensions.VRMC_springBone_limit.VRMC_springBone_limit
                             {
-                                Spherical = new UniGLTF.Extensions.VRMC_springBone_limit.SphericalLimit
+                                SpecVersion = VRMC_springBone_limit_SPEC_VERSION,
+                                Limit = new UniGLTF.Extensions.VRMC_springBone_limit.Limit
                                 {
-                                    Rotation = ReverseXToFloat4(y.m_limitSpaceOffset),
-                                    Pitch = y.m_pitch,
-                                    Yaw = y.m_yaw,
+                                    Spherical = new UniGLTF.Extensions.VRMC_springBone_limit.SphericalLimit
+                                    {
+                                        Rotation = ReverseXToFloat4(y.m_limitSpaceOffset),
+                                        Pitch = y.m_pitch,
+                                        Yaw = y.m_yaw,
+                                    }
                                 }
-                            }
-                        };
-                        glTFExtension extensions = default;
-                        UniGLTF.Extensions.VRMC_springBone_limit.GltfSerializer.SerializeTo(ref extensions, limit);
-                        joint.Extensions = extensions;
-                        break;
-                    }
+                            };
+                            glTFExtension extensions = default;
+                            UniGLTF.Extensions.VRMC_springBone_limit.GltfSerializer.SerializeTo(ref extensions, limit);
+                            joint.Extensions = extensions;
+                            break;
+                        }
+                }
             }
             return joint;
         }
diff --git a/Packages/VRM10/Runtime/IO/Vrm10Importer.cs b/Packages/VRM10/Runtime/IO/Vrm10Importer.cs
index 698d11554..3293a901b 100644
--- a/Packages/VRM10/Runtime/IO/Vrm10Importer.cs
+++ b/Packages/VRM10/Runtime/IO/Vrm10Importer.cs
@@ -650,24 +650,27 @@ namespace UniVRM10
                             if (UniGLTF.Extensions.VRMC_springBone_limit.GltfDeserializer.TryGet(gltfJoint.Extensions as glTFExtension,
                                 out var extensionSpringBoneLimit))
                             {
-                                if (extensionSpringBoneLimit.Limit.Cone is UniGLTF.Extensions.VRMC_springBone_limit.ConeLimit cone)
+                                if (VRMC_springBone_limit_Validate(go.transform, extensionSpringBoneLimit))
                                 {
-                                    joint.m_anglelimitType = UniGLTF.SpringBoneJobs.AnglelimitTypes.Cone;
-                                    joint.m_limitSpaceOffset = QuaternionFromFloat4(cone.Rotation);
-                                    joint.m_pitch = math.clamp(cone.Angle.GetValueOrDefault(), 0.0f, math.PI);
-                                }
-                                else if (extensionSpringBoneLimit.Limit.Hinge is UniGLTF.Extensions.VRMC_springBone_limit.HingeLimit hinge)
-                                {
-                                    joint.m_anglelimitType = UniGLTF.SpringBoneJobs.AnglelimitTypes.Hinge;
-                                    joint.m_limitSpaceOffset = QuaternionFromFloat4(hinge.Rotation);
-                                    joint.m_pitch = math.clamp(hinge.Angle.GetValueOrDefault(), 0.0f, math.PI);
-                                }
-                                else if (extensionSpringBoneLimit.Limit.Spherical is UniGLTF.Extensions.VRMC_springBone_limit.SphericalLimit spherical)
-                                {
-                                    joint.m_anglelimitType = UniGLTF.SpringBoneJobs.AnglelimitTypes.Spherical;
-                                    joint.m_limitSpaceOffset = QuaternionFromFloat4(spherical.Rotation);
-                                    joint.m_pitch = math.clamp(spherical.Pitch.GetValueOrDefault(), 0.0f, math.PI);
-                                    joint.m_yaw = math.clamp(spherical.Yaw.GetValueOrDefault(), 0.0f, math.PI / 2);
+                                    if (extensionSpringBoneLimit.Limit.Cone is UniGLTF.Extensions.VRMC_springBone_limit.ConeLimit cone)
+                                    {
+                                        joint.m_anglelimitType = UniGLTF.SpringBoneJobs.AnglelimitTypes.Cone;
+                                        joint.m_limitSpaceOffset = QuaternionFromFloat4(cone.Rotation);
+                                        joint.m_pitch = cone.Angle.GetValueOrDefault();
+                                    }
+                                    else if (extensionSpringBoneLimit.Limit.Hinge is UniGLTF.Extensions.VRMC_springBone_limit.HingeLimit hinge)
+                                    {
+                                        joint.m_anglelimitType = UniGLTF.SpringBoneJobs.AnglelimitTypes.Hinge;
+                                        joint.m_limitSpaceOffset = QuaternionFromFloat4(hinge.Rotation);
+                                        joint.m_pitch = hinge.Angle.GetValueOrDefault();
+                                    }
+                                    else if (extensionSpringBoneLimit.Limit.Spherical is UniGLTF.Extensions.VRMC_springBone_limit.SphericalLimit spherical)
+                                    {
+                                        joint.m_anglelimitType = UniGLTF.SpringBoneJobs.AnglelimitTypes.Spherical;
+                                        joint.m_limitSpaceOffset = QuaternionFromFloat4(spherical.Rotation);
+                                        joint.m_pitch = spherical.Pitch.GetValueOrDefault();
+                                        joint.m_yaw = spherical.Yaw.GetValueOrDefault();
+                                    }
                                 }
                             }
 
@@ -678,6 +681,60 @@ namespace UniVRM10
             }
         }
 
+        private static bool VRMC_springBone_limit_Validate(Transform node, VRMC_springBone_limit extensionSpringBoneLimit)
+        {
+            var validate = true;
+            if (extensionSpringBoneLimit.SpecVersion != Vrm10Exporter.VRMC_springBone_limit_SPEC_VERSION)
+            {
+                validate = false;
+                UniGLTFLogger.Warning($"Unknown VRMC_springBone_limit specVersion: {extensionSpringBoneLimit.SpecVersion}");
+            }
+
+            var count = 0;
+            if (extensionSpringBoneLimit.Limit != null)
+            {
+                if (extensionSpringBoneLimit.Limit.Cone is UniGLTF.Extensions.VRMC_springBone_limit.ConeLimit cone)
+                {
+                    ++count;
+                }
+                if (extensionSpringBoneLimit.Limit.Hinge is UniGLTF.Extensions.VRMC_springBone_limit.HingeLimit hinge)
+                {
+                    ++count;
+                }
+                if (extensionSpringBoneLimit.Limit.Spherical is UniGLTF.Extensions.VRMC_springBone_limit.SphericalLimit spherical)
+                {
+                    ++count;
+                }
+            }
+
+            switch (count)
+            {
+                case 0:
+                    // Limit 欠落
+                    validate = false;
+                    UniGLTFLogger.Warning($"No VRMC_springBone_limit.Limit: skip");
+                    break;
+
+                case 1:
+                    // ok
+                    break;
+
+                default:
+                    validate = false;
+                    UniGLTFLogger.Warning($"Multiple VRMC_springBone_limit.Limit: skip");
+                    break;
+            }
+
+            if (node.childCount == 0)
+            {
+                // leaf
+                UniGLTFLogger.Warning($"VRMC_springBone_limit: leaf node '{node.name}' must not have limit. skip");
+                validate = false;
+            }
+
+            return validate;
+        }
+
         private static Quaternion QuaternionFromFloat4(float[] xyzw)
         {
             var q = (xyzw != null && xyzw.Length == 4)