The San'yō Region (山陽地方 San'yō-chihō) is an area in the south of Honshū, the main island of Japan. It consists of the southern part of the Chūgoku region, facing the Seto Inland Sea. The name San'yō means "southern, sunny (yō) side of the mountains" and contrasts with the San'in or "northern, shady (in) side of the mountains".
The region is generally considered to include the prefectures of Okayama, Hiroshima and Yamaguchi. Sometimes, Harima area in Hyōgo is considered to be included in this group.
The San'yō encompasses the pre-Meiji provincial areas of Harima, Mimasaka, Bizen, Bitchu, Bingo, Aki, Suō and Nagato.