To miniaturize a transmission as a whole by shortening an axial length of a second housing supporting a high speed-side shaft.

The high speed-side shaft 17 is provided with a second bearing fitting part 17b of a large diameter at its tip end part (low speed side), besides a first bearing fitting part 17a of a large diameter. One bearing (angular ball bearing) 61 is mounted between an outer peripheral face of the first bearing fitting part 17a and an inner peripheral face of the second housing 2, and one bearing (angular ball bearing) 62 is mounted between an outer peripheral face of the second bearing fitting part 17b and an inner peripheral face of a third housing (connecting plate) 14. Whereby the high speed-side shaft 17 is rotatably supported by two bearings (angular ball bearings) 61, 62 separated from each other by a specific space at a wedge roller type transmission A side.