Abstract: Provided is a multi-antenna transmission device which can improve the reception quality when performing a repeated detection using a software value at the reception device side in a spatial multiplex MIMO system. A transmission device (1600) includes M (M is an integer not smaller than 2) transmission units (1601—1 to 1601_M) which interleave and map each of encoded data of M systems and transmit them. Each of the M transmission units (1601—1 to 1601_M) has: N (N is an integer not smaller than 2) interleavers (504A1 to 504AN (504X1 to 504XN)) which interleave the encoded data obtained from the same transmission data, by using different interleave patterns; and N antennas (510A1 to 510AN (510X1 to 510XN)) which transmit the signals obtained BY the respective interleavers.