Monbetsu Ward (Monbetsu-ku) lies on the coast of the Pacific Ocean at the outlet of the Saru River.

The entire town has an area of 992.67 square kilometres (383.27 sq mi).

Hidaka ward has an area of 563.94 square kilometres (217.74 sq mi) and Monbetsu ward has an area of 428.73 square kilometres (165.53 sq mi).

However, no services have operated between Mukawa and Samani since January 2015, due to storm damage.

Plans to restore this section of the line have been abandoned, due to declining passenger numbers and very high maintenance costs, and the section was officially closed on 1 April 2021 and replaced by a bus service.