A modulation method has a high encoding rate for generating a pattern having a lower limit for the number of successive pixels in a spatial light modulator. An information recording device includes: an encoding unit that performs error correction encoding of input data; an interleaving unit that switches the output sequence of the error correction encoding unit; and an modulation unit that performs RLL modulation of the output of the interleaving unit on the basis of an RLL modulation trellis. A corresponding information reproducing device includes: a demodulation unit that uses a posteriori probability decoding based on the RLL modulation trellis, to perform RLL demodulation for reproducing recorded information; a deinterleaving unit that reverses the sequence switching; and a decoding unit that performs error correction code decoding using a posteriori probability decoding on the basis of the error correction encoding on the output of the deinterleaving unit.