In a radio communication apparatus for forming a frame with a plurality of slots, and inserting a guard interval into each slot along with data for a mobile station to perform communication, a receive state acquisition section acquires a receive state of each mobile station, a frame format decision section decides a frame format of which guard interval length is, different for each slot based on the receive state of each mobile station, a slot assignment section assigns each slot of the frame format to data for each mobile station, and a frame format reporting section reports the decided frame format to the mobile stations via a reporting channel. The mobile station identifies the GI length based on the reported frame format and the slot number, removes the guard interval, and performs processing.