Electric power steering device

The present invention relates to an electric power steering device, which transmits rotation of an electric actuator for generating auxiliary steering power to wheels via a deceleration gear mechanism, which has a driving gear such as a worm and a driven gear such as a worm wheel which meshes with the driving gear. In an electric power steering device, a driven gear of a deceleration gear mechanism for transmitting rotation of an electric actuator for generating auxiliary steering power has a gear body made of a synthetic resin material. At least the outer periphery of a metal core ring is covered by the gear body. The gear body is molded and integrated with the core ring by injecting synthetic resin material into a mold, in which the core ring is inserted. A plurality of teeth, each of which has faces which run in the direction of the axis of rotation of the driven gear, are formed on the outer periphery of the core ring so as to be arranged at intervals in a circumferential direction. The synthetic resin material that constitutes the gear body is filled in the spaces between the teeth of the core ring.