A technique allowing an improvement in the confidentiality of information stored in a memory device. A memory controller includes a key generation part that newly generates key information for use in encryption and decryption of information at every predetermined timing, and a data conversion circuit that encrypts information to be outputted to a memory device based on the information and decrypts encrypted information inputted from the memory device based on the key information. In the data conversion circuit, each time the key generation part generates new key information, key information is updated so as to set the new key information as the key information.