Disclosed is a base station which can prevent degradation in the reception characteristics of nearby cells when carrier aggregation and channel selection are applied. In accordance with the resistance to interference of a plurality of uplink component carriers of a femtocell, a response protocol controller (101) in a base station (100) changes combination rules for the uplink component carriers and signal points which a terminal (200) in a microcell covered by the base station (100) uses in the feedback of a response signal. Information in relation to the combination rules is notified to the terminal (200). A controller (217) in the terminal (200) changes the combination rules for the uplink component carriers and the signal points of the microcell covered by the base station (100) in accordance with the information notified from the base station (100), and controls transmission of the response signal in accordance with said rules.