An error correction device error corrects without increasing in circuit scale. An encoder, includes: a first ECC encoder which interleaves a data string into n (n≧2) blocks of data strings at every m (m≧2) bits, and adds the error correction code parity; a parity encoder which creates a parity bit at every plurality of bits of the error correction code word, and adds the parity bit to said error correction code word; and a second ECC encoder, which generates a second error correction encoding, which is a linear encoding using iterative decoding. Concatenated type encoded data, where a parity bit is added to every plurality of bits, is created, so an increase of circuit scale can be prevented even if a data string is interleaved into a plurality of blocks and error correction code parity is generated.