Kunitomo Ikkansai (国友 一貫斎, November 21, 1778 – December 26, 1840), real name Kunitomo Tōbee Yoshimasa (国友 藤兵衛 能當), was a Japanese gunsmith and inventor of the late Edo period, who, after having spent several months in Edo, where he could get accustomed with Dutch wares, built Japan's first reflective telescope in 1831.

He used it to make very detailed studies of sun spots and lunar topography.

In the early 19th century, Kunitomo became an acquaintance of the Shinto theologian and nativist Hirata Atsutane, and was in regular contact with him.

Plane drawings created by Ikkansai, connecting parts for a reflecting telescope.

Nagahama City Citizen Collaboration Department, Historical Heritage Section, research into the Kunitomo Ikkansai family records.