Soft decision sections (503, 506) provisionally decide each modulated signal (502, 505) separated using an inverse matrix calculation of a channel fluctuation matrix at separation section (501). Signal point reduction sections (508, 510, 514, 516) reduce candidate signal points of a multiplexed modulated signal using the provisional decision results (504, 507). Soft decision sections (512, 518) make a correct decision using the reduced candidate signal points and obtain received data (RA, RB) of each modulated signal. This allows received data RA, RB with a good error rate characteristic to be obtained with a relatively small number of calculations without reducing data transmission efficiency.