| Locality | Post Code |
|---|---|
| Kamiwake (筑西市) | 308-0063 |
| Kanamaru (筑西市) | 308-0804 |
| Kawasumi (筑西市) | 308-0801 |
| Kawazure (筑西市) | 308-0814 |
| Kido (筑西市) | 308-0104 |
| Ko (筑西市) | 308-0021 |
| Kobana (筑西市) | 308-0862 |
| Koda (筑西市) | 308-0004 |
| Koshigi (筑西市) | 308-0077 |
| Kuchido (筑西市) | 308-0071 |
| Kujira (筑西市) | 309-1103 |
| Kuramochi (筑西市) | 300-4515 |
| Kurishima (筑西市) | 308-0061 |
| Kurogo (筑西市) | 308-0102 |
| Kuwayama (筑西市) | 309-1127 |
| Makuda (筑西市) | 308-0003 |
| Matsubara (筑西市) | 300-4541 |
| Midorimachi (筑西市) | 308-0042 |
| Miyago (筑西市) | 300-4503 |
| Miyayama (筑西市) | 300-4504 |
| Moda (筑西市) | 308-0811 |
| Morisoejima (筑西市) | 308-0861 |
| Mukokawasumi (筑西市) | 309-1117 |
| Mukoueno (筑西市) | 300-4522 |
| Murata (筑西市) | 300-4546 |
| Nabeyama (筑西市) | 300-4506 |