The Sanyo Electric Railway Main Line is a railway line in Japan operated by the private railway operator Sanyo Electric Railway. It stretches from Kobe west to Himeji via Akashi, Kakogawa and other municipalities in Hyōgo Prefecture. The line runs parallel to West Japan Railway Company JR Kobe Line, with closest sections between Sanyo Suma and Sanyo Akashi stations, and competes with the JR line for its entire stretch. Despite the name, no part of the line is located in the San’yō region.

The San'yō Main Line is a major railway line owned by JR Group companies in western Japan, connecting Kōbe Station and Moji Station, largely paralleling the coast of the Seto Inland Sea, in other words, the southern coast of western Honshu. The San'yō Shinkansen line largely parallels its route. The name Sanyō derived from the ancient region and highway San'yōdō, the road on the sunny (south) side of the mountains.