| Country: | JPN |
| Type: | National |
| Route: | 142 |
| Map Custom: | yes |
| Image Notes: | Route 142 in Shimosuwa |
| Length Km: | 77.3 |
| Length Ref: | [1] |
| Established: | 1953 |
| Direction A: | West |
| Terminus A: | in Shimosuwa, Nagano |
| Direction B: | East |
| Terminus B: | in Karuizawa, Nagano |
| Previous Type: | Route |
| Previous Route: | 141 |
| Next Type: | Route |
| Next Route: | 143 |
National Route 142 is a national highway of Japan connecting Karuizawa, Nagano and Shimosuwa, Nagano in Japan, with a total length of 77.3 km (48.03 mi).