A magnetic recording/playback apparatus in which rotational torque from the drive shaft of a single motor is capable of being transmitted to a cassette loading mechanism and a tape loading mechanism includes a worm secured to the drive shaft and a worm wheel for being meshed freely with the worm, the worm wheel being provided with a toothless portion. The drive shaft is coupled to the cassette loading mechanism via the worm wheel. During operation of the tape loading mechanism by the drive shaft, the toothless portion of the worm wheel is brought into position opposite the worm wheel so that a driving force is no longer applied to the cassette loading mechanism. When a cassette is ejected, the toothless portion of the worm wheel is shifted after a tape loading operation, thereby re-­engaging the worm wheel and worm to actuate the cassette loading mechanism.