Under control of rotation of a crankshaft 41, a friction roller 32 is pressed against a friction roller 31 in a radial direction, so as to achieve torque transmission between the rollers 31, 32. An inter-roller radial pressing reaction is canceled as an internal force in bearing supports 23, 25, with no input to a housing 11. The reaction causes a radial displacement of a bearing-fitting portion provided with inner and outer bearings 21, 42 in double layer arrangement, wherein the radial displacement is larger than that of a bearing-fitting portion provided with a bearing 18, 19, 22 in single arrangement, so as to cause unbalanced contact between rollers 31, 32. In order to prevent this, support stiffness of bearing support 23 against the inter-friction-roller radial pressing reaction is set higher than that of bearing support 25.