The Great Seto Bridge (瀬戸大橋, Seto Ō-hashi?), or Seto-Ohashi Bridge, is a series of double deck bridges connecting Okayama and Kagawa prefectures in Japan across a series of five small islands in the Seto Inland Sea. Built over the period 1978–1988, it is one of the three routes of the Honshū-Shikoku Bridge Project connecting Honshū and Shikoku islands. At 13.1 km long, it ranks as the world's longest two-tiered bridge system.

Crossing the bridge takes about 20 minutes by car or train. The ferry crossing before the bridge was built took about an hour. The non-discounted toll from Kojima, Kurashiki (Okayama Prefecture on the Honshū side) to Sakaide (Kagawa Prefecture on the Shikoku side) is ¥3,500, and vice-versa.