To obtain maximum throughput in accordance with characteristics of a propagation path, a radio transmission device having a plurality of transmitting antennas (18a, 18b) for transmitting a transmission signal in units of sub-carriers by performing spatial multiplexing or without performing spatial multiplexing is provided that includes a sub-carrier modulation part 11 modulating the input transmission signal for each sub-carrier, a transmission signal allocation part 13 allocating the transmission signal modulated for each of the sub-carriers to each of the transmitting antennas, and a transmission control part 12 that determines a multiplexing number for performing spatial multiplexing for each sub-carrier based on information received from another radio communication device as an opposite party, and outputs the determined multiplexing number to the sub-carrier modulation part and the transmission signal allocation part.