A magnetic recording and/or reproducing apparatus in which the decoding error rate is to be lowered through realization of the high-performance encoding and the high efficiently decoding. To this end, a magnetic recording and/or reproducing apparatus 50 includes, in its recording system, an error correction coder 51 for error correction encoding input data, an interleaver 52 for interleaving data supplied from the error correction coder 51 for re-arraying the data sequence, a modulation encoder 53 for modulation encoding the data from the interleaver 52 in a predetermined fashion and an interleaver 54 for interleaving the data from the modulation encoder 53 for re-arraying the data sequence. The magnetic recording and/or reproducing apparatus 50 also includes, in its reproduction system, a channel, modulation and error correction turbo decoder 64 formed by concatenation of an error correction soft decoder and a modulation decoder for decoding the input data with the interposition of two deinterleavers and two interleavers.