Koumac () is a commune in the North Province of New Caledonia, an overseas territory of France in the Pacific Ocean.
On 5 January 1977 about 46% of the territory of Koumac was detached and became the commune of Poum.
The town of Koumac serves as a regional centre for the far north region of Grande Terre island. It has good connections north and south by road, and several shops, industrial suppliers, and utilities. It is a centre for mining employment, formerly dominated by the mine at Tiébaghi which closed in 1990, and other current operations. Koumac Airport is located a couple kilometres north of the commune with regular flights to Nouméa.
Koumac has a tropical savanna climate (Köppen Aw), although there is still some rain in the dry season which peaks between July and October.
Athlete Arnjolt Beer was born here.