diff --git a/Assets/VRM/Runtime/LookAt/CurveMapper.cs b/Assets/VRM/Runtime/LookAt/CurveMapper.cs
index b5d0a8f3f..d64586a49 100644
--- a/Assets/VRM/Runtime/LookAt/CurveMapper.cs
+++ b/Assets/VRM/Runtime/LookAt/CurveMapper.cs
@@ -17,6 +17,9 @@ namespace VRM
         [Range(0, 90.0f)]
         public float CurveYRangeDegree;
 
+        // zero 除算などを回避する閾値
+        public const float MIMIMUM_INPUT_MAX_VALUE = 1e-5f;
+
         public CurveMapper(float xRange, float yRange)
         {
             CurveXRangeDegree = xRange;
@@ -61,6 +64,13 @@ namespace VRM
 
         public float Map(float src)
         {
+            if (CurveXRangeDegree < MIMIMUM_INPUT_MAX_VALUE)
+            {
+                // https://github.com/vrm-c/UniVRM/issues/2452
+                return 0;
+                // or CurveYRangeDegree ?
+            }
+
             if (src < 0)
             {
                 src = 0;
diff --git a/Assets/VRM10/Runtime/Components/LookAt/CurveMapper.cs b/Assets/VRM10/Runtime/Components/LookAt/CurveMapper.cs
index 55dcba9ff..f451c291e 100644
--- a/Assets/VRM10/Runtime/Components/LookAt/CurveMapper.cs
+++ b/Assets/VRM10/Runtime/Components/LookAt/CurveMapper.cs
@@ -17,6 +17,9 @@ namespace UniVRM10
         [Range(0, 90.0f)]
         public float CurveYRangeDegree;
 
+        // zero 除算などを回避する閾値
+        public const float MIMIMUM_INPUT_MAX_VALUE = 1e-5f;
+
         public CurveMapper(float xRange, float yRange)
         {
             CurveXRangeDegree = xRange;
@@ -33,6 +36,13 @@ namespace UniVRM10
 
         public float Map(float src)
         {
+            if (CurveXRangeDegree < MIMIMUM_INPUT_MAX_VALUE)
+            {
+                // https://github.com/vrm-c/UniVRM/issues/2452
+                return 0;
+                // or CurveYRangeDegree ?
+            }
+
             if (src < 0)
             {
                 src = 0;