The present patent application is for solving a problem of occurrence of efforts required to replace a signature and consumption of time induced by the efforts.A secure memory card of the present patent application has a communication unit receiving encryption data and data to be signed; an encryption/decryption unit subjecting arbitrary data to encryption/decryption processing; a checking unit for checking the data to be signed against a signature stored in the encryption data decrypted by the encryption/decryption unit; a determination unit for determining validity of the data to be signed on the basis of a checking result of the checking unit; and a storage unit for storing, as valid data, data other than the signature of the encryption data including the signature when the determination unit determines that the data to be signed are valid.