A microprocessor includes a decryption unit that decrypts information to be utilized by a processor core to obtain plaintext information when the acquired information is encrypted; and a plaintext information storing unit that stores the plaintext information. The microprocessor also includes a protected attribute adding unit that adds a protected attribute indicating one of protection and non-protection to the plaintext information based on whether the decryption has been performed; an access request acquiring unit that acquires an access request to the plaintext information; a request type identifying unit that identifies a type of request of the access request; and an access controlling unit that controls an access to the plaintext information based on the type of request and the protected attribute.