diff --git a/pkg/modules/2_backend_optimizer.go b/pkg/modules/2_backend_optimizer.go
index fbd1f5a..ab44031 100644
--- a/pkg/modules/2_backend_optimizer.go
+++ b/pkg/modules/2_backend_optimizer.go
@@ -23,13 +23,13 @@ func NewOptimizerImpl(pluginOptions *proto.PluginOptions) *OptimizerImpl {
 	return &OptimizerImpl{schemaByRef: jsonschema.NewOrderedSchemaMap(), pluginOptions: pluginOptions}
 }
 
-const refCountKey = "refCount"
+const linkedFromEntrypoint = "linkedFromEntrypoint"
 
 func (o *OptimizerImpl) Optimize(registry *jsonschema.Registry, entrypointMessage pgs.Message) {
 	entrypointSchemaRef := toRefId(entrypointMessage)
 	entrypointSchema := registry.GetSchema(entrypointSchemaRef.String())
 
-	o.increaseSchemaRefCount(registry, entrypointSchemaRef.String())
+	o.checkAndMarkSchemaToVisitable(registry, entrypointSchemaRef.String())
 	o.visitSchema(registry, entrypointSchema)
 
 	o.optimizeDefinitions(registry)
@@ -39,9 +39,9 @@ func (o *OptimizerImpl) optimizeDefinitions(registry *jsonschema.Registry) {
 	var deleteKeys []string
 	for _, key := range registry.GetKeys() {
 		schema := registry.GetSchema(key)
-		if schema.GetExtrasItem(refCountKey) == nil {
+		if schema.GetExtrasItem(linkedFromEntrypoint) == nil {
 			deleteKeys = append(deleteKeys, key)
-		} else if schema.GetExtrasItem(refCountKey).(int) == 0 {
+		} else if schema.GetExtrasItem(linkedFromEntrypoint).(bool) == false {
 			deleteKeys = append(deleteKeys, key)
 		}
 	}
@@ -66,17 +66,19 @@ func (o *OptimizerImpl) getEntrypointMessage(messages []pgs.Message, fileOptions
 	return nil
 }
 
-func (o *OptimizerImpl) increaseSchemaRefCount(registry *jsonschema.Registry, ref string) {
+// return true if first visit to schema
+func (o *OptimizerImpl) checkAndMarkSchemaToVisitable(registry *jsonschema.Registry, ref string) bool {
 	schema := registry.GetSchema(ref)
 	if schema == nil {
 		panic(fmt.Sprintf("schema not found: %s", ref))
 	}
 
-	rawValue := schema.GetExtrasItem(refCountKey)
+	rawValue := schema.GetExtrasItem(linkedFromEntrypoint)
 	if rawValue == nil {
-		schema.SetExtrasItem(refCountKey, int(1))
+		schema.SetExtrasItem(linkedFromEntrypoint, true)
+		return true
 	} else {
-		schema.SetExtrasItem(refCountKey, rawValue.(int)+1)
+		return false
 	}
 }
 
@@ -86,8 +88,9 @@ func (o *OptimizerImpl) visitSchema(registry *jsonschema.Registry, schema *jsons
 	}
 
 	if !schema.Ref.IsEmpty() {
-		o.increaseSchemaRefCount(registry, schema.Ref.String())
-		o.visitSchema(registry, registry.GetSchema(schema.Ref.String()))
+		if o.checkAndMarkSchemaToVisitable(registry, schema.Ref.String()) {
+			o.visitSchema(registry, registry.GetSchema(schema.Ref.String()))
+		}
 	}
 	o.visitSchemaMap(registry, schema.Definitions)
 
diff --git a/testdata/README.md b/testdata/README.md
index efd30f8..e1c1571 100644
--- a/testdata/README.md
+++ b/testdata/README.md
@@ -82,6 +82,8 @@ proto-optional optional이 있다면 required에서 빠지는지 테스트
 
 proto-message message가 object로 잘 전환되는지 테스트
 
+proto-circular-dependent 순환 의존성이 있는 메시지를 잘 전환하는지 테스트
+
 proto-enum enum이 enum으로 잘 전환되는지 테스트
 
 plugin-preserve-field-name-false json_name이 잘 적용되는지 테스트
diff --git a/testdata/cases/proto-circular-dependent/test.proto b/testdata/cases/proto-circular-dependent/test.proto
new file mode 100644
index 0000000..cd7cd07
--- /dev/null
+++ b/testdata/cases/proto-circular-dependent/test.proto
@@ -0,0 +1,23 @@
+syntax = "proto3";
+
+package tests;
+
+import "jsonschema.proto";
+
+option (pubg.jsonschema.file) = {entrypoint_message: "Values"};
+
+message Values {
+  SelfReference entry = 1;
+}
+
+//message CircularDependentTwoDepth {
+//  CircularDependentTwoDepth0 child = 1;
+//}
+//
+//message CircularDependentTwoDepth0 {
+//  CircularDependentTwoDepth parent = 1;
+//}
+
+message SelfReference {
+  SelfReference self = 1;
+}
diff --git a/testdata/cases/proto-circular-dependent/test.schema.json b/testdata/cases/proto-circular-dependent/test.schema.json
new file mode 100644
index 0000000..1f076f7
--- /dev/null
+++ b/testdata/cases/proto-circular-dependent/test.schema.json
@@ -0,0 +1,36 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$ref": "#/$defs/.tests.Values",
+  "$defs": {
+    ".tests.Values": {
+      "properties": {
+        "entry": {
+          "$ref": "#/$defs/.tests.Values.entry"
+        }
+      },
+      "type": "object",
+      "required": [
+        "entry"
+      ]
+    },
+    ".tests.Values.entry": {
+      "$ref": "#/$defs/.tests.SelfReference"
+    },
+    ".tests.SelfReference": {
+      "properties": {
+        "self": {
+          "$ref": "#/$defs/.tests.SelfReference.self"
+        }
+      },
+      "type": "object",
+      "required": [
+        "self"
+      ],
+      "description": "message CircularDependentTwoDepth {\n  CircularDependentTwoDepth0 child = 1;\n}\n\nmessage CircularDependentTwoDepth0 {\n  CircularDependentTwoDepth parent = 1;\n}"
+    },
+    ".tests.SelfReference.self": {
+      "$ref": "#/$defs/.tests.SelfReference"
+    }
+  },
+  "type": "object"
+}
\ No newline at end of file
diff --git a/testdata/cases/proto-circular-dependent/test.yaml b/testdata/cases/proto-circular-dependent/test.yaml
new file mode 100644
index 0000000..a112f44
--- /dev/null
+++ b/testdata/cases/proto-circular-dependent/test.yaml
@@ -0,0 +1,11 @@
+name: "proto-circular-dependent"
+description: "Test for circular dependent message in proto file"
+
+inputFiles: ["test.proto"]
+inputParameters: {}
+
+expectResultFiles: ["test.schema.json"]
+expectResultIsNull: false
+expectFail: false
+
+expectedBehaviorDescription: ""