A method and apparatus of releasing an uplink radio resource in a wireless communication system, is provided. A user equipment (UE) receives first feedback channel allocation information from a base station (BS), and allocates a uplink radio resource to a feedback channel based on the first feedback channel allocation information. The UE also receives second feedback channel allocation information including an feedback channel release command which indicate the release of the allocated uplink radio resource to the feedback channel, and transmits a release confirm message to the BS through a hybrid automatic repeat request (HARQ) feedback channel (HFBCH) for transmitting a HARQ feedback. the UE releases the allocated uplink radio resource to the feedback channel.