diff --git a/Altob.NtuInvoiceGateway/Pages/Invoice.cshtml b/Altob.NtuInvoiceGateway/Pages/Invoice.cshtml
index 46be77f..1abf25d 100644
--- a/Altob.NtuInvoiceGateway/Pages/Invoice.cshtml
+++ b/Altob.NtuInvoiceGateway/Pages/Invoice.cshtml
@@ -176,6 +176,15 @@
             const successAlert = document.getElementById('formSuccessMessage');
             const submitButtonContainer = document.getElementById('submitButtonContainer');
 
+            const showError = (message) => {
+                if (!errorAlert || !errorText) {
+                    alert(message);
+                    return;
+                }
+                errorText.textContent = message;
+                errorAlert.classList.remove('d-none');
+            };
+
             const hideError = () => {
                 if (!errorAlert || !errorText) {
                     return;
@@ -186,6 +195,13 @@
 
             errorCloseBtn?.addEventListener('click', hideError);
 
+            const optionalGroup = [
+                document.querySelector('input[name="InvoiceData.Email"]'),
+                document.querySelector('input[name="InvoiceData.CarrierID"]'),
+                document.querySelector('input[name="InvoiceData.BuyerIdentifier"]'),
+                document.querySelector('select[name="InvoiceData.LoveCode"]')
+            ];
+
             const form = document.querySelector('form[method="post"]');
             if (!form) {
                 return;
@@ -218,6 +234,19 @@
                     return;
                 }
 
+                const filledCount = optionalGroup.reduce((count, field) => {
+                    if (field && field.value.trim() !== '') {
+                        return count + 1;
+                    }
+                    return count;
+                }, 0);
+
+                if (filledCount === 0) {
+                    event.preventDefault();
+                    showError('Email、手機條碼、購買者統編、捐贈碼需擇一填寫，請填寫任一項。');
+                    return;
+                }
+
                 hideError();
                 lockForm();
             });