A low-profile magnetic recording and/or reproducing apparatus is disclosed in which a drum (3) is disposed substantially in front of a supply reel disc (1), a capstan (4) and a pinch roller (5) are disposed substantially in front of a take-up reel disc (2), a reel clutch mechanism (8) extends from the capstan (4) to a position located between the supply reel disc (1) and the take-up reed disc (2), and a drive mechanism (11) for driving a tape loading mechanism, a tape tension servo mechanism, a pinch roller displacement mechanism, etc. comprises a gear train (11) disposed in a space extending arcuately along the drum (3) and defined between the drum (3), supply reel disc (1), reel clutch mechanism (8) and the capstan (4). Since the drive mechanism (11) thus arranged does not overlap any of the components (1 - 5) which are controlled in thickness by the width of a magnetic tape, a substantial reduction of the overall thickness of the apparatus is possible.