To avoid useless re-transmission waiting as much as possible in a mobile station in a mobile communication system corresponding to HSDPA.

The mobile station capable of corresponding to the HSDPA employing H-ARQ which is provided with a control unit for releasing re-transmission waiting state if it is detected that the re-transmission waiting state continues for at least a predetermined time or more is used. In this case, it should be determined that the release permits transmission of new data via HS-PDSCH when next HS-SCCH destined to its own station is received. Also, the apparatus is provided with a storage unit for storing already received data to be synthesized with retransmitted data, and the release performs control to permit deletion of the already received data of the storage unit or overwriting of the already received data onto a storage region.