| Locality | Postal Code |
|---|---|
| Postal/ZIP Codes in Usujiricho (函館市) | 041-1613 |
| Postal/ZIP Codes in Wakamatsucho (函館市) | 040-0063 |
| Postal/ZIP Codes in Yachigashiracho (函館市) | 040-0046 |
| Postal/ZIP Codes in Yamanote (函館市) | 041-0836 |
| Postal/ZIP Codes in Yanagawacho (函館市) | 040-0015 |
| Postal/ZIP Codes in Yanagimachi (函館市) | 040-0002 |
| Postal/ZIP Codes in Yasuracho (函館市) | 041-1612 |
| Postal/ZIP Codes in Yayoicho (函館市) | 040-0056 |
| Postal/ZIP Codes in Yoshikawacho (函館市) | 040-0077 |
| Postal/ZIP Codes in Yunohamacho (函館市) | 042-0933 |
| Postal/ZIP Codes in Yunokawacho (函館市) | 042-0932 |
| Postal/ZIP Codes in Zenikamecho (函館市) | 042-0922 |