Monbetsu (紋別市; -shi) is a city located in Abashiri, Hokkaido, Japan, on the Sea of Okhotsk.
Most of Monbetsu's economy is dedicated to fishing for cold-water species such as crab. During the summertime, when the icebergs melt, sailors from Russia are a common sight in the city.
As of 2003, the city has an estimated population of 27,764 and the density of 33.44 persons per km². The total area is 830.36 km².
The city was founded on July 1, 1954.