A mobile station apparatus and method for retransmitting data in a reverse direction upon receiving a retransmission request for the data transmitted in the reverse direction from a bases station after transmitting the data in the reverse direction in a mobile communication system supporting hybrid automatic retransmission request (HARQ). The apparatus comprises a radio frequency (RF) receiver for receiving a retransmission control signal for the reverse data over a forward link; and a controller for determining whether to retransmit the reverse data using the retransmission control signal received from the RF receiver, and controlling transmission of retransmission data using a traffic-to-pilot power ratio (TPR) included in the retransmission control signal.