An error correction decoding device is configured to decode a multi-valued modulation symbol having a dimension of D and a number of bits per dimension of M (M is an integer of 2 or more) from each of D (D is an integer of 1 or more)
pulse amplitude modulation symbols. An error correction decoding device is provided with: a soft
decision unit (1) that acquires each
pulse amplitude modulation symbol from a communication symbol sequence in which D
pulse amplitude modulation symbols are arranged, calculates, on the basis of each pulse
amplitude modulation symbol, a positive or negative first hard decision bit indicating the logarithmic
posterior probability ratio of each of M bits included in a multi-valued modulation symbol, and outputs the calculated first hard decision bit to a second hard decision bit that indicates the logarithmic
posterior probability ratio of each of the M bits included in the multi-valued modulation symbol; calculating an absolute value of each logarithmic
posterior probability ratio as a first reliability; and an exclusive-OR calculation unit (2) that calculates the exclusive-OR of the D * M first hard decision bits calculated by the soft
decision unit (1). Furthermore, the error correction decoding device is provided with: a reliability selection unit (3) which compares the D * M first reliability degrees calculated by the soft
decision unit (1) with each other, selects one first reliability degree from among the D * M first reliability degrees on the basis of the result of the comparison, and outputs the one first reliability degree as a second reliability degree; and a soft
decision error correction decoding unit (4) that performs soft
decision error correction decoding on the result of the
exclusive OR operation performed by the
exclusive OR operation unit (2) and the second reliability.