The Sanyō Main Line (山陽本線, Sanyō-honsen) is the JR main railway line in western Japan, connecting Kobe Station and Moji Station. The Sanyo Shinkansen line runs largely parallel to its route.

The San'yo Main Line is operated by the following two JR companies.

The Wadamisaki Line, a short section of line between Hyogo and Wadamisaki stations in Kobe is technically part of the San'yō Main Line.