A disc music box for playing a melody comprises a base (21); a music box disc (1) having a plurality of engaging drive parts (3) and a drive hole (4); a plurality of music box petals (27a) provided on the base; a plurality of star wheels (26) each guided and revolved by one of the engaging drive parts, a turn plate (23) provided coaxially with the music box disc and having a detecting member (42) thereon; a motor (M) provided on the base; a transmission mechanism (24) disposed between the turn plate and the motor to transmit the drive force of the motor to the turn plate; a drive projection (23d) provided on the turn plate for engagement with the drive hole of the music box disc for positioning the music box disc; and a switch (43) provided on the base for engagement with the detecting member of the turn plate when the music box disc makes one rotation.