This arithmetic logical unit outputs data to be used in checking the final result of an AES unit that encrypts a plain text block into an encrypted text block based on AES operation, and includes an arithmetic unit for computing parity data created based on XOR operation from an encryption key to be used as a key during AES encryption, parity data created based on XOR operation from a plain text block, and an AES operation halfway result output from the AES unit, and outputting a value that is equivalent to parity data created based on XOR operation from the final result of the AES unit.