diff --git a/nestjs-BE/server/src/crdt/operation.ts b/nestjs-BE/server/src/crdt/operation.ts
index ef2704c7..11d7c3af 100644
--- a/nestjs-BE/server/src/crdt/operation.ts
+++ b/nestjs-BE/server/src/crdt/operation.ts
@@ -141,6 +141,10 @@ export class OperationMove<T> extends Operation<T> {
     const node = tree.get(this.id);
     const oldParentId = node.parentId;
 
+    if (tree.isAncestor(this.parentId, this.id)) {
+      return { operation: this, oldParentId };
+    }
+
     tree.removeNode(this.id);
     tree.attachNode(this.id, this.parentId);
     return { operation: this, oldParentId };
diff --git a/nestjs-BE/server/src/crdt/tree.ts b/nestjs-BE/server/src/crdt/tree.ts
index 772152a2..bcf7a0ae 100644
--- a/nestjs-BE/server/src/crdt/tree.ts
+++ b/nestjs-BE/server/src/crdt/tree.ts
@@ -41,6 +41,7 @@ export class Tree<T> {
 
     const targetIndex = parentNode.children.indexOf(targetId);
     if (targetIndex !== -1) parentNode.children.splice(targetIndex, 1);
+    targetNode.parentId = '0';
 
     return this.nodes.get(targetId);
   }