Kuromatsunai (黒松内町, Kuromatsunai-chō) is a town located in Shiribeshi, Hokkaido, Japan.

As of 24 May 2020 the town had an estimated population of 2,739, and a density of 7.2 persons per km2.

Kuromatsunai is located in the southern part of Shiribeshi Subprefecture and while close to both the Sea of Japan and the Pacific Ocean, the town itself has no coastline.

The town, being the northernmost area of Japan in which beech trees grow naturally, has had the beech tree designated a natural treasure.

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