To realize silent and smooth power transmission, obtain high transmission efficiency, and reduce size, weight, and costs.

Two guide rollers 37a, 37b and a movable roller 38 moving when transmitting torque are provided between an outer ring 32 and a high speed side shaft 17. A wedge roller type transmission A is a reduction gear, and a drive shaft 51 of an electric motor 50 is integrally connected with the high speed side shaft 17. A rotated body X is mounted on a low speed side shaft 3. The rotated body X is, for example, photoreceptor drums 141C to 141K, a transfer roller, paper conveyance rollers 162, 167 (paper feeding roller), or a drive roller 132 for a paper conveyance belt.