Oregon Route 104, known as the Fort Stevens Highway No. 104 (see Oregon highways and routes), is an Oregon state highway which connects US 101 near Warrenton with Fort Stevens State Park.

The OR 104 designation was applied to the Fort Stevens Highway in 2002 as part of Oregon's project to assign route numbers to previously unrouted highways.

The southern terminus of OR 104 is at a junction with US 101 near south of Warrenton. It heads due north for 6 miles (9.7 km), ending at the entrance to Fort Stevens State Park near Hammond. The southern portion of the route, and its spur constitute an old portion of US 101.

Oregon Route 104S is a spur route of Oregon Route 104, and connects OR 104 to U.S. Route 101 and U.S. Route 101 Business in Warrenton. The route is designated as the Fort Stevens Spur of the Fort Stevens Highway No. 104.