To improve the life and the reliability by maintaining the lubricating condition successfully.

Traction oil is forcedly introduced from an external pump (an illustration omitted) via an oil filler port 81, and traction oil is guided from a guide passage 86 of a second housing 2 via each guide passage a, b, c, d. Then, traction oil is supplied from the axial guide passage d to contact parts (traction parts), in which a lubricating condition is apt to thin, between a high speed shaft 17 and respective rollers 37a... via an axial guide passage e of the high speed shaft 17 and a plurality of radial guide passages f (series). This enables the fully forced-feed lubrication of a traction part.