An electric power steering apparatus comprises: a pinion provided on a shaft co-rotatable with a steering member; a steering shaft including a rack meshed with the pinion, the steering shaft being movable in an axial direction thereof; a steering shaft guiding device; and a motion converting mechanism. The steering shaft guiding device guides the steering shaft for axial movement, and biases the steering shaft toward the pinion. The motion converting mechanism includes a rotary cylinder surrounding the steering shaft and driven by a steering assist electric motor, and converts rotation of the rotary cylinder into the axial movement of the steering shaft. The steering shaft is supported by the rotary cylinder, the pinion and a guide. The pinion is located between the rotary cylinder and the guide axially of the steering shaft.