for the clutch the clutch member 84 is prevented from falling out from the reel hub 32 by the rotation restricting ribs 90 and the rotation restricting grooves 82 note that as shown in fig2 and fig3 the rotating shaft 100 of the drive device has a rotating shaft portion 102 a disc shaped rotating table 104 extends integrally at the top end of the rotating shaft portion 102 the driving gear 108 which can mesh together with the reel gear 44 of the recording tape cartridge 10 is formed in an annular form at the top surface of and at the outer peripheral edge portion of the rotating table 104 further a magnet 106 which is substantially formed in the shape of a disc is disposed coaxially at the top surface of the rotating table 104 at the radial direction inner side of the driving gear 108 the releasing projection 110 which abuts the pushing operating surface 88 of the clutch member 84 is formed at the axially central portion of the rotating table 104 next operation of the recording tape cartridge 10 having the reel 30 of the above described structure will be described at the recording tape cartridge 10 when the recording tape cartridge 10 is not in use due to the urging force of the compression coil spring 76 the brake member 60 is.