To provide a general structure which is applicable to various models and simplified by removing a bearing housing for pressing a first bearing and reducing the number of parts and press-in man-hours in a pressure imparting mechanism of an electric power steering device in which a worm gear and a worm wheel are engaged with each other and the first bearing supporting one end of a worm shaft is movable relative to a gear housing, and is spring-biased in a direction to tighten the engagement.

A spring hook shaft 30 is provided at an end of a worm gear 10 supported by a first bearing 20. The spring hook shaft axially projects from the first bearing 20 and projects toward the outside from a long hole 32 of a gear housing 8. A bearing 34 for a spring hook is provided around the spring hook shaft, and an extension spring 36 is extended between the bearing 34 for the spring hook and the gear housing 8. The worm gear 10 is biased in a direction to tighten the engagement with a worm wheel 12. Accordingly, a bearing housing which has been conventionally essential can be omitted.