濑户大桥是日本一座位于本州（冈山县仓敷市）到四国（香川县坂出市）之间，跨越濑户内海的桥梁，属于本州四国连络桥路网的三条路线之一。濑户大桥是沿岛连接冈山和香川县之间5个岛的6座桥的总称，桥梁全长达9.4km。全桥由多座吊桥、斜张桥与梁桥链接，构成壮观的桥梁群。

该桥在1978年（昭和53年）10月10日开工，施工耗时近10年，到1988年（昭和63年）4月10日始全面通车。该桥为公路铁路两用桥，上层为4车道的高速公路（濑户中央自动车道），下层为JR四国濑户大桥线。

The Great Seto Bridge(瀬戸大橋,Seto Ōhashi) 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 1978–88, it is one of the three routes of the Honshū–Shikoku Bridge Project connecting Honshū and Shikoku islands, and the only one with railroad connections included. At 13.1 kilometers (8.1 mi), it ranks as the world's longest two-tiered bridge system.