To determine the influence of the forest type on bats in terms of roosting sites and foraging habitats, we compared species richness and abundance (total and by species) of forest-dwelling bats in old-growth forests and conifer (larch) plantations in central Japan. We also compared species richness and abundance of the bats in riparian and non-riparian habitats, and compared the old-growth forest stands with the larch plantation stands to examine differences in the forest stand structures. Species richness, total bat abundance, and the abundances of two tree-roosting specialists, the Ikonnikovi's Myotis (Myotis ikonnikovi) and the Ussurian tube-nosed bat (Murina ussuriensis), were significantly higher in the old-growth forests than in the conifer plantations. The old-growth forests contained larger trees and more snag trees, which provided roosting sites for tree-roosting species. Species richness, total bat abundance, and abundances of the two tree-roosting specialists and the Japanese large-footed bat (My. macrodactylus) were also significantly higher in the riparian habitats than in the non-riparian habitats. The riparian old-growth forest appears to be an important habitat for forest-dwelling bats. Our results suggest that a shift from old-growth forests to conifer plantations has negative effects on forest-dwelling bats, particularly tree-roosting specialists.