Mashike (増毛町, Mashike-chō) is a town located in Rumoi Subprefecture, Hokkaido, Japan.

It has a rugged terrain sandwiched between the ocean to the west and the mountains to the east, and most settlements are concentrated on the coast.

However, the coast west of Beskari is lined with steep cliffs, and until the opening of Japan National Route 231 in 1981, it was an "island on land" with almost no means of transportation other than by boat.

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

In terms of national politics, the town is part of the Hokkaidō 10th district of the lower house of the Diet of Japan.

Mashike was the terminus of the JR Hokkaido Rumoi Main Line which ran from Fukagawa, but the section of the line between Rumoi and Mashike was closed on 4 December 2016, owing to declining passenger use, and the town no longer has any passenger rail service.