A steering assist apparatus includes a camera for picking up the rear side of a vehicle, a monitor disposed in a driver's compartment of the vehicle, a steering angle sensor for detecting a steering angle of a steering wheel, and a display controlling unit for displaying on the monitor an image through said camera when the vehicle reverses and for superimposing and displaying on said monitor a guide display for assisting the drive of the vehicle when the vehicle is to be parked. The guide display includes a steering start guide line fixedly displayed in a predetermined position of an image field of the monitor for guiding a steering start position for parking, and a steering amount guide mark moved and displayed along the steering start guide line on the image field of the monitor in correspondence with a steering angle of the steering wheel detected by the steering angle sensor. The driver performs the steering operation of the vehicle while recognizing the position for the opposite turning of the steering wheel and the steering amount and the steering start position for parking on the basis of the image on the rear side of the vehicle and the steering amount guide mark and the steering start guide line.