Abstract: The present invention is an auto reverse mechanism for tape recorder/playback devices. In the present invention, if the tape travel in either direction is completed to stop the rotation of the reel turntables, a detector at first detects the halt of the reel turntables through the change-over clutch, and mechanically transmits it to the trigger. The trigger then drives the intermittent drive by the drive force of the drive belt mechanism through the drive force transmission, from a position away from the linkage with the drive force transmission to a position for the linkage with it.