A reception device (300, 400, 1100) that receives (S101, S201) a multiplexed signal into which a plurality of data series have been multiplexed by superposition coding, and derives (S104, S105, S205, S206, S208, S214) the plurality of data series from the multiplexed signal, the plurality of data series including a first data series in a first layer and a second data series in a second layer, the reception device (300, 400, 1100) comprising: a receiver (330, 430, 1130) that receives (S101, S201) the multiplexed signal; a first demapper (310, 411, 1110) that demaps (S102, S203, S207) the multiplexed signal with a second modulated symbol stream of the second data series being included in the multiplexed signal as an undetermined signal component, to generate (S102, S203, S207) a first bit likelihood stream of the first data series; a second demapper (310, 421, 1110) that demaps (S103, S204, S213) the multiplexed signal to generate a second bit likelihood stream of the second data series; a first decoder (313, 413, 1113) that performs (S104, S205, S208) error control decoding on the first bit likelihood stream to derive (S104, S205, S208) the first data series; and a second decoder (323, 423, 1123) that performs (S105, S206, S214) error control decoding on the second bit likelihood stream to derive (S105, S206, S214) the second data series; and characterized by an encoder that performs error control coding on the first data series derived by the first decoder to generate a first bit stream of the first data series; a mapper that maps the first bit stream to generate a first modulated symbol stream; a delayer that delays the multiplexed signal received by the receiver for a predetermined time length; a subtractor that subtracts the first modulated symbol stream from the multiplexed signal delayed by the delayer; wherein the second demapper: - demaps the multiplexed signal, with the first modulated symbol stream being included in the multiplexed signal as an undetermined signal component, to generate the second bit likelihood stream, when a signal-to-noise ratio of the multiplexed signal satisfies a predetermined requirement, and - demaps the multiplexed signal from which the first modulated symbol stream has been subtracted to generate the second bit likelihood stream, when the signal-to-noise ratio of the multiplexed signal fails to satisfy the predetermined requirement. a receiver (330, 430, 1130) that receives (S101, S201) the multiplexed signal; a first demapper (310, 411, 1110) that demaps (S102, S203, S207) the multiplexed signal with a second modulated symbol stream of the second data series being included in the multiplexed signal as an undetermined signal component, to generate (S102, S203, S207) a first bit likelihood stream of the first data series; a second demapper (310, 421, 1110) that demaps (S103, S204, S213) the multiplexed signal to generate a second bit likelihood stream of the second data series; a first decoder (313, 413, 1113) that performs (S104, S205, S208) error control decoding on the first bit likelihood stream to derive (S104, S205, S208) the first data series; and a second decoder (323, 423, 1123) that performs (S105, S206, S214) error control decoding on the second bit likelihood stream to derive (S105, S206, S214) the second data series; and characterized by an encoder that performs error control coding on the first data series derived by the first decoder to generate a first bit stream of the first data series; a mapper that maps the first bit stream to generate a first modulated symbol stream; a delayer that delays the multiplexed signal received by the receiver for a predetermined time length; a subtractor that subtracts the first modulated symbol stream from the multiplexed signal delayed by the delayer; wherein the second demapper: - demaps the multiplexed signal, with the first modulated symbol stream being included in the multiplexed signal as an undetermined signal component, to generate the second bit likelihood stream, when a signal-to-noise ratio of the multiplexed signal satisfies a predetermined requirement, and - demaps the multiplexed signal from which the first modulated symbol stream has been subtracted to generate the second bit likelihood stream, when the signal-to-noise ratio of the multiplexed signal fails to satisfy the predetermined requirement. - demaps the multiplexed signal, with the first modulated symbol stream being included in the multiplexed signal as an undetermined signal component, to generate the second bit likelihood stream, when a signal-to-noise ratio of the multiplexed signal satisfies a predetermined requirement, and - demaps the multiplexed signal from which the first modulated symbol stream has been subtracted to generate the second bit likelihood stream, when the signal-to-noise ratio of the multiplexed signal fails to satisfy the predetermined requirement.