A transmission device (500, 600, 700) that multiplexes a plurality of data series including. a first data series in a first layer and a second data series in a second layer, and transmits a multiplexed signal into which the plurality of data series have been multiplexed, the transmission device (500, 600, 700) comprising: a transmitter (540, 640, 740) that transmits the multiplexed signal; characterized by a first mapper (513, 613, 713) that maps, using a QPSK constellation, a first bit stream of the first data series to generate a first modulated symbol stream of the first data series; a second mapper (523, 623, 723) that maps, using a Nu-256QAM constellation, a second bit stream of the second data series to generate a second modulated symbol stream of the second data series; a converter (525, 625, 723) that subjects the second modulated symbol stream to conversion in accordance with the first modulated symbol stream to control a polarity of a real part and a polarity of an imaginary part of each modulated symbol in the second modulated symbol stream to: - reverse the polarity of the real part of a second modulated symbol in the second modulated symbol stream, when a real part of a first modulated symbol in the first modulated symbol stream has a predetermined polarity, and - reverse the polarity of the imaginary part of the second modulated symbol, when an imaginary part of the first modulated symbol has a predetermined polarity; and a superposition unit (514, 524, 530; 614, 624, 630; 714, 724, 730) that superposes the first modulated symbol stream and the second modulated symbol stream at a predetermined amplitude ratio to superpose the first modulated symbol and the second modulated symbol at the predetermined amplitude ratio and to generate the multiplexed signal, the second modulated symbol stream having been subjected to the conversion in accordance with the first modulated symbol stream. a transmitter (540, 640, 740) that transmits the multiplexed signal; characterized by a first mapper (513, 613, 713) that maps, using a QPSK constellation, a first bit stream of the first data series to generate a first modulated symbol stream of the first data series; a second mapper (523, 623, 723) that maps, using a Nu-256QAM constellation, a second bit stream of the second data series to generate a second modulated symbol stream of the second data series; a converter (525, 625, 723) that subjects the second modulated symbol stream to conversion in accordance with the first modulated symbol stream to control a polarity of a real part and a polarity of an imaginary part of each modulated symbol in the second modulated symbol stream to: - reverse the polarity of the real part of a second modulated symbol in the second modulated symbol stream, when a real part of a first modulated symbol in the first modulated symbol stream has a predetermined polarity, and - reverse the polarity of the imaginary part of the second modulated symbol, when an imaginary part of the first modulated symbol has a predetermined polarity; and - reverse the polarity of the real part of a second modulated symbol in the second modulated symbol stream, when a real part of a first modulated symbol in the first modulated symbol stream has a predetermined polarity, and - reverse the polarity of the imaginary part of the second modulated symbol, when an imaginary part of the first modulated symbol has a predetermined polarity; and a superposition unit (514, 524, 530; 614, 624, 630; 714, 724, 730) that superposes the first modulated symbol stream and the second modulated symbol stream at a predetermined amplitude ratio to superpose the first modulated symbol and the second modulated symbol at the predetermined amplitude ratio and to generate the multiplexed signal, the second modulated symbol stream having been subjected to the conversion in accordance with the first modulated symbol stream.