PURPOSE: To make it possible to smoothly shift and transmit ultra high speed power by producing a local pressure at a contact point of each of rollers with the use of a planetary roller mechanism having a special roller configuration and a hydraulic pressurizing mechanism so as to generate a high traction for power transmission.

CONSTITUTION: At least three planetary roller 3 have each convex curved surfaces at both shoulder parts of its outer peripheral surface and are made, at the shoulder parts, into press-contact with two left and right outer contact rings 4, 4' respectively having inner peripheral surfaces of cone-like shapes with equal inclined angles so that the planetary rollers 3 are made into press- contact with the outer periphery of a sun roller 2 under the presence of oil. Further, at least one of the outer contact rings 4, 4' is movable axially and is pressed against the planetary rollers 3 by means of a ring-like cylinder 11. Further, each of the planetary rollers 3 is concentrically split into two parts, that is, a roller part 3a and an outer peripheral side ring part 3b with a gap 16 therebetween, and further, the sun roller 2 is coupled to a high speed shaft 5, and the two left and right outer contact rings 4, 4' are coupled to a low speed shaft 8 through a carrier 7.