Provided is a receiver device that can switch between transmission methods, while minimizing increase in the number of blind decryption iterations and the amount of signaling needed for acknowledgement. In this device, a receiver part (201) receives a signal mapped to any of a plurality of mapping candidates; and according to application levels established for each of the plurality of mapping candidates, a control signal processor (205) performs blind decryption of the plurality of mapping candidates, employing either a first transmission method using a single antenna port to carry out precoding based on feedback information from the receiver device, or a second transmission method involving transmission diversity employing multiple antenna ports.