An orthogonal signal from a modulated signal of the digital terrestrial broadcast is produced. Then, an adder carrier-combines the orthogonal signal and an interpolated signal into an interpolated orthogonal signal, which is in turn demodulated by a DQPSK demodulation section. A demodulated signal is produced from a modulated signal of the digital satellite broadcast. A transmission path coding section produces transport stream data. A DQPSK mapping section re-demodulates the transport stream data to produce an orthogonal signal. A sync detection section asynchronously detects a demodulated signal demodulated by the DQPSK demodulation section and a demodulated signal produced by a time deinterleave section in the transmission path coding section. The detected time difference is set as a delay time of a delay circuit so as to delay the orthogonal signal, thereby producing the interpolated signal to be carrier-combined by the adder in order to provide improved reception quality.