To provide an excellent data recording and reproducing apparatus, a data recording and reproducing method, a program, and a recording medium in which efficiency of redundancy by an error correction code is good and data can be stably reproduced.

Influence of reduction of a transfer rate by slip is lightened by setting (F104) constitution of a first error correction code (C1) unit in accordance with the slip. Also, error correction can be performed even for a random error and a burst error in a wider range by using the first error correction code unit and a second error correction code (C2) unit, stable data reproduction can be performed without reducing transfer speed by avoiding retry operation, while necessary error correction capability is secured. In particular, the occurrence of dispersion of error correction capability due to variation of redundancy degree by influence of the slip is avoided, and the influence of data transfer speed by the slip is made small, and by setting constitution of the second error correction code (C2) unit also in accordance with the slip, it is made suitable setting even for the transfer rate and storage capacity.