A mobile station device includes a device for transmitting an access packet to a base station device, and a device for retransmitting the access packet when no acknowledgement is received from the base station in response to the transmission of the access packet. The mobile station device also includes a received power processing section for sequentially storing received power of a pilot signal transmitted from the base station, and determining transmission power at the retransmitting time of the access packet on the basis of these stored contents. A signal receiving section obtains interference amount information showing an interference amount in the base station. A data transmitting section transmits the access packet using power according to the interference amount information.