diff --git a/Assets/VRM10/Runtime/FastSpringBone/Blittables/BlittableSpring.cs b/Assets/VRM10/Runtime/FastSpringBone/Blittables/BlittableSpring.cs
index 36f6d7401..4657e68fd 100644
--- a/Assets/VRM10/Runtime/FastSpringBone/Blittables/BlittableSpring.cs
+++ b/Assets/VRM10/Runtime/FastSpringBone/Blittables/BlittableSpring.cs
@@ -1,5 +1,5 @@
 using System;
-using UnityEngine.Serialization;
+using UnityEngine;
 
 namespace UniVRM10.FastSpringBones.Blittables
 {
@@ -13,5 +13,6 @@ namespace UniVRM10.FastSpringBones.Blittables
         public BlittableSpan logicSpan;
         public int centerTransformIndex;
         public int transformIndexOffset;
+        public Vector3 externalForce;
     }
 }
\ No newline at end of file
diff --git a/Assets/VRM10/Runtime/FastSpringBone/System/FastSpringBoneBufferCombiner.cs b/Assets/VRM10/Runtime/FastSpringBone/System/FastSpringBoneBufferCombiner.cs
index b1b513c69..8d547d6ab 100644
--- a/Assets/VRM10/Runtime/FastSpringBone/System/FastSpringBoneBufferCombiner.cs
+++ b/Assets/VRM10/Runtime/FastSpringBone/System/FastSpringBoneBufferCombiner.cs
@@ -38,6 +38,8 @@ namespace UniVRM10.FastSpringBones.System
         public NativeArray<BlittableCollider> Colliders => _colliders;
         public NativeArray<BlittableLogic> Logics => _logics;
 
+        public bool HasBuffer => _batchedBuffers != null && _batchedBuffers.Length > 0;
+
         public void Register(FastSpringBoneBuffer buffer)
         {
             _buffers.AddLast(buffer);
diff --git a/Assets/VRM10/Runtime/FastSpringBone/System/FastSpringBoneScheduler.cs b/Assets/VRM10/Runtime/FastSpringBone/System/FastSpringBoneScheduler.cs
index 064d37360..3df9b05d8 100644
--- a/Assets/VRM10/Runtime/FastSpringBone/System/FastSpringBoneScheduler.cs
+++ b/Assets/VRM10/Runtime/FastSpringBone/System/FastSpringBoneScheduler.cs
@@ -8,6 +8,7 @@ namespace UniVRM10.FastSpringBones.System
     public sealed class FastSpringBoneScheduler : IDisposable
     {
         private readonly FastSpringBoneBufferCombiner _bufferCombiner;
+        public Vector3 ExternalForce { get; set; }
 
         public FastSpringBoneScheduler(FastSpringBoneBufferCombiner bufferCombiner)
         {
@@ -18,6 +19,10 @@ namespace UniVRM10.FastSpringBones.System
         {
             var handle = default(JobHandle);
             handle = _bufferCombiner.ReconstructIfDirty(handle);
+            if (!_bufferCombiner.HasBuffer)
+            {
+                return handle;
+            }
             
             handle = new PullTransformJob
                 {
@@ -32,6 +37,7 @@ namespace UniVRM10.FastSpringBones.System
                 Springs = _bufferCombiner.Springs,
                 Transforms = _bufferCombiner.Transforms,
                 DeltaTime = Time.deltaTime,
+                ExternalForce = ExternalForce
             }.Schedule(_bufferCombiner.Springs.Length, 1, handle);
 
             handle = new PushTransformJob
diff --git a/Assets/VRM10/Runtime/FastSpringBone/System/FastSpringBoneService.cs b/Assets/VRM10/Runtime/FastSpringBone/System/FastSpringBoneService.cs
index d3e103977..597d963c3 100644
--- a/Assets/VRM10/Runtime/FastSpringBone/System/FastSpringBoneService.cs
+++ b/Assets/VRM10/Runtime/FastSpringBone/System/FastSpringBoneService.cs
@@ -27,6 +27,12 @@ namespace UniVRM10.FastSpringBones.System
             }
         }
 
+        public Vector3 ExternalForce
+        {
+            get => _fastSpringBoneScheduler.ExternalForce;
+            set => _fastSpringBoneScheduler.ExternalForce = value;
+        }
+
         /// <summary>
         /// 専有しているインスタンスを破棄する
         /// </summary>
diff --git a/Assets/VRM10/Runtime/FastSpringBone/System/UpdateFastSpringBoneJob.cs b/Assets/VRM10/Runtime/FastSpringBone/System/UpdateFastSpringBoneJob.cs
index 6c2315861..8f74e0182 100644
--- a/Assets/VRM10/Runtime/FastSpringBone/System/UpdateFastSpringBoneJob.cs
+++ b/Assets/VRM10/Runtime/FastSpringBone/System/UpdateFastSpringBoneJob.cs
@@ -22,6 +22,7 @@ namespace UniVRM10.FastSpringBones.System
         [NativeDisableParallelForRestriction] public NativeArray<BlittableTransform> Transforms;
 
         public float DeltaTime;
+        public Vector3 ExternalForce;
 
         public void Execute(int index)
         {
@@ -43,7 +44,6 @@ namespace UniVRM10.FastSpringBones.System
                     ? Transforms[spring.centerTransformIndex + transformIndexOffset]
                     : (BlittableTransform?)null;
 
-
                 // 親があったら、親に依存するTransformを再計算
                 if (parentTransform.HasValue)
                 {
@@ -62,7 +62,7 @@ namespace UniVRM10.FastSpringBones.System
                 var parentRotation = parentTransform?.rotation ?? Quaternion.identity;
 
                 // verlet積分で次の位置を計算
-                var external = joint.gravityDir * joint.gravityPower * DeltaTime;
+                var external = (joint.gravityDir * joint.gravityPower + ExternalForce) * DeltaTime;
                 var nextTail = currentTail
                                + (currentTail - prevTail) * (1.0f - joint.dragForce) // 前フレームの移動を継続する(減衰もあるよ)
                                + parentRotation * logic.localRotation * logic.boneAxis *