When performing secure processing using confidential information that needs to be confidential, the secure processing device according to the present invention prevents the confidential information from being exposed by an unauthorized analysis such as a memory dump. A signature generation device that provides a message M with a signature by using a signature key comprises: a split key storage unit that stores split secret keys obtained by splitting the signature key d into at least two, a signature key generation equation F for calculating the split secret keys to obtain the signature key d, and a signature generation equation; a signature key generation identical equation generation unit that generates a signature key generation identical equation G for obtaining the same result as the signature generation equation F, with use of an associative law, a distributive law, and a commutative law; a combined split key generation unit that generates a plurality of combined split keys that are each a result of calculating the split secret keys, and that are to be arguments for the signature key generation identical equation G; and a signature generation unit that provides the message with the signature, based on the signature key generation identical equation G and the split secret keys.