diff --git a/src/components/01_branch-management/FormBranchInformation.vue b/src/components/01_branch-management/FormBranchInformation.vue
index c36df0b5..33003dce 100644
--- a/src/components/01_branch-management/FormBranchInformation.vue
+++ b/src/components/01_branch-management/FormBranchInformation.vue
@@ -58,6 +58,11 @@ function formatCode(input: string | undefined, type: 'code' | 'number') {
           :label="$t('formDialogHqAbbreviation')"
           for="input-abbreviation"
           :model-value="view ? formatCode(abbreviation, 'code') : abbreviation"
+          :rules="[
+            (val) =>
+              (val && val.length > 0 && /[a-zA-Z]+/.test(val)) ||
+              $t('formDialogInputHqAbbreviation'),
+          ]"
           @update:model-value="(v) => (abbreviation = v as string)"
         />
         <q-input
diff --git a/src/i18n/en-US/form-dialog.ts b/src/i18n/en-US/form-dialog.ts
index 38e0ff0e..5bf6e927 100644
--- a/src/i18n/en-US/form-dialog.ts
+++ b/src/i18n/en-US/form-dialog.ts
@@ -4,6 +4,8 @@ export default {
 
   // Branch & HQ
   formDialogHqAbbreviation: 'Head Office Abbreviation',
+  formDialogInputHqAbbreviation: 'Please enter Head Office Abbreviation',
+
   formDialogTitleImg: 'Office Image',
   formDialogBtnImg: 'Add Office Image',
 
diff --git a/src/i18n/th-th/form-dialog.ts b/src/i18n/th-th/form-dialog.ts
index 2a9230c7..327ccb23 100644
--- a/src/i18n/th-th/form-dialog.ts
+++ b/src/i18n/th-th/form-dialog.ts
@@ -4,6 +4,8 @@ export default {
 
   // Branch & HQ
   formDialogHqAbbreviation: 'ตัวย่อสำนักงานใหญ่',
+  formDialogInputHqAbbreviation: 'โปรดระบุตัวย่อสำนักงานใหญ่',
+
   formDialogTitleImg: 'ภาพสำนักงาน',
   formDialogBtnImg: 'เพิ่มรูปสำนักงาน',