To stabilize lubricating function at each contact part by arranging a thickness eliminating part continued in a circumferential direction on a part on an inner circum ferential surface of an outer ring which is brought into contact with a roller, in a transmission provided with multistage roller formed by multiply arranging a roller groups in a radial direction between a sun roller and the outer ring.

A sun roller 1 is mounted on one end of a high speed rotary shaft 7 journaled to one housing 6, and a plurality of first roller 3a is arranged on the fore-and-aft position of the sun roller 1. A plurality of second rollers 3b are supported to the housing 6 by a supporting shaft 9, and abuts on a rotary shaft of the first rollers 3a. An outer ring 2 which is brought into contact with the second roller 3b is mounted on an outer peripheral part of a holder 16 on a low speed rotary shaft 13 journaled to the other housing 12. A thickness eliminating part 4 continued to a circumferential direction and formed by eliminating a thickness of a part of an area is formed on an inner circumferential surface of the outer ring 2 so as to ensure lubricating property, increase contact surface pressure of a roller contact part, and improve power transmission performance.