Two species of Nyctalus, the large noctule N. lasiopterus aviator THOMAS, 1911 and the lesser noctule N. noctula motoyoshii KURODA, 1934 (=Nyctalus noctula NAMIE, 1889), have been known from Japan. The former is common everywhere, but the latter seems to be rare and is known only by two missing syntypes studied by Namie. The author recently had an opportunity to examine several specimens of a kind of smaller noctule obtained from Japan, which were remarkably different from motoyoshii and much similar to the typical noctula. This raised a doubt about the taxonomic status of motoyoshii. Then, the original description and the figures of this species were carefully examined and several characters differing from the genus Nyctalus were found out by the author. On the other hand, all the characters of motoyoshii mentioned in the original description well agree with Vespertilio from Japan. Therefore, motoyoshii seems to be nothing but a synonym of Vespertilio superans which is rather common to the type locality of the former, Chichibu, central Japan.