| Locality | Postal Code |
|---|---|
| Aono (茂原市) | 299-4106 |
| Ashiami (茂原市) | 297-0066 |
| Chiyodacho (茂原市) | 297-0023 |
| Chubu (茂原市) | 297-0027 |
| Chuzenji (茂原市) | 297-0057 |
| Daida (茂原市) | 297-0044 |
| Dobyo (茂原市) | 297-0028 |
| Enokikambo (茂原市) | 299-4115 |
| Enokikambotobichi (茂原市) | 299-4118 |
| Hagiwaracho (茂原市) | 297-0018 |
| Hayano (茂原市) | 297-0037 |
| Hayanoshinden (茂原市) | 297-0031 |
| Higashimobara (茂原市) | 297-0032 |
| Home (茂原市) | 299-4113 |
| Honkogutsuwa (茂原市) | 297-0005 |
| Honno (茂原市) | 299-4114 |
| Ishigami (茂原市) | 297-0058 |
| Kambayashi (茂原市) | 297-0019 |
| Kamimobara (茂原市) | 297-0052 |
| Kaminagayoshi (茂原市) | 297-0036 |
| Kamioda (茂原市) | 299-4124 |
| Katsura (茂原市) | 299-4127 |
| Katsuratobichi (茂原市) | 299-4128 |
| Kawashimatobichi (茂原市) | 297-0014 |
| Kayaba (茂原市) | 299-4111 |
| Kisaki (茂原市) | 297-0016 |