According to an embodiment, a memory controller includes: a coding unit that performs an error correction coding process for user data to generate first to n-th parities and performs the error correction coding process for each of the first to n-th parities to generate first to n-th external parities; and a decoding unit that performs an error correction decoding process using the user data, the first to n-th parities, and the first to n-th external parities. A generator polynomial used to generate an i-th parity is selected on the basis of a generator polynomial used to generate the first to (i−1)-th parities.