A mobile communication system that is a wireless communication system using the AMC scheme and does not require any transmission/reception of control signals between a base station apparatus and a mobile station apparatus during controlling of the transmission/reception of the mobile station apparatus. In this mobile communication system, the mobile station apparatus measures reception quality of a downlink signal transmitted by the base station apparatus, and uses an uplink control channel to transmit, to the base station apparatus, downlink signal quality information (CQI) corresponding to the measured reception quality. The base station apparatus receives the downlink signal quality information CQI to control the data transmission to the mobile station apparatus. The base station apparatus judges whether the downlink signal quality information CQI transmitted by the mobile station apparatus is present, and controls, based on the result of this judgment, the downlink signal to be transmitted to the mobile station apparatus.