A memory controller includes: a memory access part which writes, to memory, an encrypted data acquired by encrypting information data, a first code for error detection based on the information data, and a second code for error detection based on the encrypted data and which reads the encrypted data, the first and second codes from the memory during a monitoring process being executed with a monitoring part; a decryption part for acquiring readout data by decrypting the encrypted data; and an error detection part which acquires a first error detection result by performing an error detection process on the readout data and the first code and a second error detection result by performing an error detection process on the encrypted data and the second code. The monitoring part stops the decryption part during the monitoring process and determines a deterioration level of memory based on the second error detection result.