Abstract: The information block that is sequentially extracted from an information sequence and that serves as a conversion unit is divided into a plurality of sub-blocks, Then, counting is performed of the information items number of at least one of "0" and "1" that is contained in each sub-block for each sub-block of a plurality of the thus-divided sub-blocks. Then, there is performed, according to the counted result that has been thus obtained, inversion yes/no determination of whether the original information contained in each sub-block should be inverted under the consideration of minimizing the difference between the number of codes "0", and the number of codes "1", contained in the code block as a whole.