diff --git a/src/app/editor/[projectId]/FlowchartEditor.tsx b/src/app/editor/[projectId]/FlowchartEditor.tsx
index 8567611..1942a47 100644
--- a/src/app/editor/[projectId]/FlowchartEditor.tsx
+++ b/src/app/editor/[projectId]/FlowchartEditor.tsx
@@ -116,8 +116,19 @@ function FlowchartEditorInner({ initialData }: FlowchartEditorProps) {
   }, [getViewportCenter, setNodes])
 
   const handleAddVariable = useCallback(() => {
-    // TODO: Implement in US-026
-  }, [])
+    const position = getViewportCenter()
+    const newNode: Node = {
+      id: nanoid(),
+      type: 'variable',
+      position,
+      data: {
+        variableName: '',
+        operation: 'set',
+        value: 0,
+      },
+    }
+    setNodes((nodes) => [...nodes, newNode])
+  }, [getViewportCenter, setNodes])
 
   const handleSave = useCallback(() => {
     // TODO: Implement in US-034