Abstract: A recording/reproducing apparatus using optical magnetic tape, comprises an objective lens for focusing the light generated from a light source, and an acousto optic scanner and an ultrasonic wave generator for vertically or horizontally displacing the focal point of the objective lens in order to scan a light beam onto the optical magnetic tape transferred along the outer periphery of a rotating drum. According to the disclosed principles, recording/reproducing at high speeds is possible, and a high data-transmission speed is obtained with a low rotating speed of the rotating drum, so that the instrument is stabile, small, and simple in construction.