Abstract: In a reel assembly of a tape cassette a one-way clutch mechanism is provi which serves to prevent rotation of the reel in the direction required for the purposes of rewinding a tape thereon. The one-way clutch mechanism includes a slipway channel which extends circumferentially of the axis of rotation of the reel. The reel assembly includes a first clutch member which is designed to be driven by the power output shaft of the winding mechanism and a second member which is designed to be held fast with respect to the cassette. A slipway channel is formed at an interface between the first and second clutch members such that a portion of the channel is formed in the first member and a portion of the channel is formed in the second member. A pawl displacing ring is mounted in the slipway channel so that it bears against the second member and is drivingly connected to the first member by means of a pawl.