diff --git a/webui/src/components/Shared/Form.js b/webui/src/components/Shared/Form.js
index 469dc73d3..a9edf2228 100644
--- a/webui/src/components/Shared/Form.js
+++ b/webui/src/components/Shared/Form.js
@@ -165,14 +165,15 @@ class Form extends Component {
     const { formData, status, errors } = data;
     const { disableSubmitButton } = this.state;
 
-    // I think there is a library bug React or Jsonschema
-    // For workaround, I'll simply add 'formData' in setState
-    this.setState({
-      disableSubmitButton: status !== 'editing' || errors.length !== 0,
-      formData
-    });
-
-    console.log(data);
+    let check = (status !== 'editing' || errors.length !== 0);
+    if (check !== disableSubmitButton) {
+      // I think there is a library bug React or Jsonschema
+      // For workaround, I'll simply add 'formData' in setState
+      this.setState({
+        disableSubmitButton: check,
+        formData
+      });
+    }
   }
 
   render() {
@@ -191,6 +192,7 @@ class Form extends Component {
       schema,
       uiSchema,
       formData,
+      validate,
       onHide,
       onSubmit
     } = this.props;
@@ -211,6 +213,7 @@ class Form extends Component {
               fields={fields}
               FieldTemplate={CustomFieldTemplate}
               liveValidate
+              validate={validate}
               showErrorList={false}
               transformErrors={transformErrors}
               autocomplete="off"
diff --git a/webui/src/components/Subscriber/Edit.js b/webui/src/components/Subscriber/Edit.js
index 931752358..08bfd4c8c 100644
--- a/webui/src/components/Subscriber/Edit.js
+++ b/webui/src/components/Subscriber/Edit.js
@@ -164,19 +164,35 @@ class Edit extends Component {
     onSubmit: PropTypes.func,
   }
 
+  validate = (formData, errors) => {
+    const { subscribers } = this.props;
+    const { imsi } = formData;
+    
+    if (subscribers.filter(subscriber => subscriber.imsi === imsi).length > 0) {
+      errors.imsi.addError("IMSI has already been registered");
+    }
+
+    return errors;
+  }
+
   render() {
+    const {
+      validate,
+    } = this;
+
     const {
       visible,
       onHide,
-      onSubmit
+      onSubmit,
     } = this.props;
 
     return (
       <Form 
-        schema={schema}
-        uiSchema={uiSchema}
         visible={visible}
         title="Create Subscriber"
+        schema={schema}
+        uiSchema={uiSchema}
+        validate={validate}
         onHide={onHide}
         onSubmit={onSubmit}>
       </Form>
diff --git a/webui/src/containers/SubscriberContainer.js b/webui/src/containers/SubscriberContainer.js
index 79da685ba..de632525a 100644
--- a/webui/src/containers/SubscriberContainer.js
+++ b/webui/src/containers/SubscriberContainer.js
@@ -141,6 +141,7 @@ class SubscriberContainer extends Component {
           />
         <FloatingButton onClick={formHandler.show}/>
         <Subscriber.Edit
+          subscribers={subscribers.data}
           visible={form.visible} 
           onHide={formHandler.hide}
           onSubmit={formHandler.submit} />