Phyllonorycter watanabei is a moth of the Gracillariidae family. It is known from the islands of Hokkaido, Shikoku, Honshu and Kyushu in Japan and from the Russian Far East. The wingspan is 5.5–6 mm. The larvae feed on Pourthiaea villosa and Pyrus ussuriensis. They mine the leaves of their host plant. The mine is ptychonomous and located in the space between two veins of the lower surface of the leaf.