A radio base station eNB according to the present invention includes: a CQI reception unit 11 configured to receive CQI in PDSCH from a mobile station UE; a CQI adjustment unit 13 configured to adjust the received CQI based on a transmission acknowledgement result for a downlink data signal transmitted via the PDSCH; a selectable TF number calculation unit 22 configured to calculate a selectable maximum transport block size based on the number of mobile stations UE in each scheduling unit period; and an MCS selection unit 15 configured to select a modulation scheme and a coding rate, which are to be applied to each resource blocks in the PDSCH, based on the adjusted CQI and a transmission format corresponding to the calculated selectable maximum transport block size.