A radio communication system comprising: a base station; a relay station (200, 200a) configured to perform wireless communications with the base station; and a mobile station (300, 300a) configured to perform wireless communications with the base station or relay station (200, 200a), wherein: the relay station (200, 200a) includes: a first radio communication unit configured to transmit a first message about random access to the base station, and to receive from the base station a radio signal including a second message about the random access; and the base station includes: a second radio communication unit configured to receive the first message, and to transmit the second message; and a first controller configured to control transmission timing of the second message based on whether a transmission source of the received first message is the relay station (200, 200a) or the mobile station, wherein the first controller is further configured to limit the transmission of radio signals from the base station to the relay station (200, 200a) in subframes of the relay station (200, 200a) that are not configured as Multimedia Broadcast multicast service Single Frequency Network subframes. a base station; a relay station (200, 200a) configured to perform wireless communications with the base station; and a mobile station (300, 300a) configured to perform wireless communications with the base station or relay station (200, 200a), wherein: the relay station (200, 200a) includes: a first radio communication unit configured to transmit a first message about random access to the base station, and to receive from the base station a radio signal including a second message about the random access; and the base station includes: a second radio communication unit configured to receive the first message, and to transmit the second message; and a first controller configured to control transmission timing of the second message based on whether a transmission source of the received first message is the relay station (200, 200a) or the mobile station, wherein the first controller is further configured to limit the transmission of radio signals from the base station to the relay station (200, 200a) in subframes of the relay station (200, 200a) that are not configured as Multimedia Broadcast multicast service Single Frequency Network subframes. the relay station (200, 200a) includes: a first radio communication unit configured to transmit a first message about random access to the base station, and to receive from the base station a radio signal including a second message about the random access; and a first radio communication unit configured to transmit a first message about random access to the base station, and to receive from the base station a radio signal including a second message about the random access; and the base station includes: a second radio communication unit configured to receive the first message, and to transmit the second message; and a first controller configured to control transmission timing of the second message based on whether a transmission source of the received first message is the relay station (200, 200a) or the mobile station, wherein the first controller is further configured to limit the transmission of radio signals from the base station to the relay station (200, 200a) in subframes of the relay station (200, 200a) that are not configured as Multimedia Broadcast multicast service Single Frequency Network subframes. a second radio communication unit configured to receive the first message, and to transmit the second message; and a first controller configured to control transmission timing of the second message based on whether a transmission source of the received first message is the relay station (200, 200a) or the mobile station, wherein the first controller is further configured to limit the transmission of radio signals from the base station to the relay station (200, 200a) in subframes of the relay station (200, 200a) that are not configured as Multimedia Broadcast multicast service Single Frequency Network subframes.