In an OFDM transmitter apparatus for transmitting transmit signals, which are output from first and second OFDM transmit circuits, utilizing two mutually orthogonal polarized waves, a single carrier wave generator is provided in common for the OFDM transmit circuits, and a frequency converter in each OFDM transmit circuit multiplies a baseband signal by a common carrier wave, which is output from the carrier wave generator, to convert the baseband signal to a radio signal.