A transmitting apparatus that transmits signals from a plurality of antennas, and can improve the security of communication compared with a conventional system. In this apparatus, an antenna changing section (105) stores an antenna change pattern in internal memory, and each time a clock signal is input, generates an antenna change signal directing an antenna change in accordance with the antenna change pattern, and outputs this signal to an antenna selection section (106). Based on the antenna change signal, the antenna selection section (106) selects two different antennas from among the transmitting antennas (107-1 through 107-3) as transmitting antennas of transmit signal A output from a radio section (104-1) and transmit signal B output from a radio section (104-2), and performs radio transmission of transmit signal A and transmit signal B using the selected transmitting antennas.