| Locality | Postal Code |
|---|---|
| Osawa (茂原市) | 299-4125 |
| Oshiba (茂原市) | 297-0033 |
| Oshibi (茂原市) | 297-0075 |
| Others (茂原市) | 297-0000 |
| Rokutadai (茂原市) | 297-0056 |
| Sangaya (茂原市) | 297-0042 |
| Sarubukuro (茂原市) | 297-0041 |
| Sencho (茂原市) | 297-0002 |
| Senzawa (茂原市) | 299-4103 |
| Shibana (茂原市) | 299-4126 |
| Shibuya (茂原市) | 297-0008 |
| Shimizu (茂原市) | 299-4101 |
| Shimonagayoshi (茂原市) | 297-0035 |
| Shimooda (茂原市) | 299-4123 |
| Shinkogutsuwa (茂原市) | 297-0006 |
| Shoyoshi (茂原市) | 297-0076 |
| Sumida (茂原市) | 297-0053 |
| Tachiki (茂原市) | 297-0043 |
| Takada (茂原市) | 299-4116 |
| Takashi (茂原市) | 297-0029 |
| Takashicho (茂原市) | 297-0021 |
| Takashidai (茂原市) | 297-0078 |
| Tobudai (茂原市) | 297-0015 |
| Togo (茂原市) | 297-0017 |
| Tsunashima (茂原市) | 297-0055 |
| Uchinagaya (茂原市) | 297-0062 |