State Route 557 (SR 557, OH 557) is a two-lane north–south state highway in the central portion of Ohio, a U.S. state. The highway's southern terminus is at a T-intersection with State Route 643 approximately 2 miles (3.2 km) north of Baltic. Its northern terminus is at a T-intersection with the duplex of U.S. Route 62 and State Route 39 nearly 1.5 miles (2.4 km) west of the unincorporated community of Berlin.

Established in the late 1930s, State Route 557 runs exclusively within Holmes County. All of the highway is inclusive in the Amish Country Byway, an officially designated National Scenic Byway.

State Route 557 exists entirely within the southeastern quadrant of Holmes County. The route is not included in the National Highway System.

The entire route is in Holmes County.