A wireless base station apparatus performing wireless communication with a mobile station apparatus includes: a transmission unit to transmit data to the mobile station apparatus; a reception unit to receive a delivery result for the data from the mobile station apparatus; and a control unit to determine whether reception processing through a first channel is performed or parallel reception processing through the first channel and a second channel is performed on the basis of a radio line quality between the wireless base station apparatus and the mobile station apparatus or an amount of processing in the reception unit if the transmission unit transmits a permission notification permitting the transmission through the first channel to the mobile station apparatus, where the reception unit performs the reception processing in accordance with the result of the determination to receive the delivery result transmitted through the first channel or the second channel.