| Country: | JPN |
| Type: | National |
| Route: | 170 |
| Alternate Name: | Osaka Outer Loop Line |
| Map Custom: | yes |
| Length Km: | 74.0 |
| Length Ref: | [1] |
| Established: | 1 April 1963 |
| Direction A: | North |
| Direction B: | South |
| Terminus B: | in Izumisano, Osaka |
| Previous Type: | Route |
| Previous Route: | 169 |
| Next Type: | Route |
| Next Route: | 171 |
National Route 170 is a national highway of Japan connecting Takatsuki, Osaka and Izumisano, Osaka in Japan, with a total length of 74 km (45.98 mi).
Route 170 was originally designated on 18 May 1953 from Wakayama to Matsusaka (this was Route 41 from 1945 to 1953). After it was extended to Tsu, the route was redesignated as Route 42 on 1 April 1959. Route 170 was reassigned on a route from Takatsuki to Hashimoto on 1 April 1963. On 1 April 1982 the terminus was moved from Hashimoto to Izumisano.