Motoyama (本山町, Motoyama-chō) is a town located in Nagaoka District, Kōchi Prefecture, Japan.

During the Edo period, the area was part of the holdings of Tosa Domain ruled by the Yamauchi clan from their seat at Kōchi Castle.

Motoyama has a mayor-council form of government with a directly elected mayor and a unicameral town council of ten members.

In terms of national politics, the village is part of Kōchi 1st district of the lower house of the Diet of Japan.

The economy of Motoyama is based forestry, agriculture and the raising of Japanese Brown beef cattle.