According to one embodiment of the present invention, a broadcast signal receiver comprises a first OFDM demodulator and a second OFDM demodulator which perform OFDM demodulation on a first M*M-QAM-type broadcast signal and on a second M*M-QAM-type broadcast signal, respectively; a first frequency deinterleaver and a second frequency deinterleaver which deinterleave the first OFDM-demodulated broadcast signal and the second OFDM-demodulated broadcast signal, respectively, in a frequency domain; a first frame parser and a second frame parser which parse frame structures of the first deinterleaved broadcast signal and the second deinterleaved broadcast signal, respectively; a first time deinterleaver and a second time deinterleaver which deinterleave the first frame-parsed broadcast signal and the second frame-parsed broadcast signal, respectively, in a time domain; a MIMO decoder which performs MIMO decoding on the first time-deinterleaved broadcast signal and on the second time-deinterleaved broadcast signal to output a first M-QAM-type signal and a second M-QAM-type signal; and a merger which merges the first M-QAM-type signal and the second M-QAM-type signal.