The present invention relates to a data processing apparatus and a data processing method which can improve the tolerance to errors of data. A demultiplexer replaces, in accordance with an allocation rule for allocating code bits of an LDPC code to symbol bits representative of symbols, mb bits from among the code bits and sets the code bits after the replacement as symbol bits of b symbols. According to the allocation rule, where groups into which the code bits and the symbol bits are to be grouped in response to an error probability thereof are set as code bit groups and symbol bit groups, respectively, a combination of any of the code bit groups and the symbol bit group of the symbol bits to which the code bits of the code bit group are to be allocated and bit numbers of the code bits and the symbols bits are prescribed.