According to one embodiment, a memory controller includes an encoding unit that generates a first parity for every user data and a second parity for two or more user data and the corresponding first parity, a memory interface unit that the non-volatile memory to write and read the user data and the parities to and from the non-volatile memory, and a decoding unit that performs an error correction decoding process using the user data, and the parities. The error correction decoding processing that uses both the first parity and the second parity has at least A (a correcting capability of the first parity)+B (a correcting capability of the second parity) bits of correcting capability for the first user data and its first and second parities and for the second user data and its first and second parities.