A parallel residue arithmetic operation unit is provided to reduce processing delay, and to make an additional multiplier or a residue arithmetic circuit unnecessary, so that a circuit can become small in size. In the parallel residue arithmetic operation unit, a parallel CRC calculation circuit includes input terminals to which input data are divided into a plurality of sub-blocks and the sub-blocks are input in parallel, an initial value generating unit for generating a part CRC corresponding to the forefront of each sub-block as an initial value, a part CRC generating unit for receiving the part CRC corresponding to the forefront of each sub-block as the initial value and sequentially generating a residue part CRC in accordance with a recurrent equation, AND units for calculating logical multiplications of part CRC values, and a cumulative adding unit for cumulatively adding values output from the AND units.