An error correction block generated by performing error correction coding to the user data is divided into b number of sectors (b: a natural number), each sector having a number of bits (a: a natural number), the sector is divided into c number of sub-sectors (c: a natural number) and bits are distributed to each of the c number of sub-sectors, arrangement order of the bits is randomized for each sub-sector to which the bits are distributed, the c number of sub-sectors in which the arrangement order of the bits is randomized are combined to generate an interleaved sector, the interleaved sector is divided into c/d (d: a natural number, c≠d, and c>d) and e number of divided interleaved sectors (e: a natural number, e≠b, and b>e) are combined to generate a pre-modulation block, which is modulated by a modulation rule.