A memory system includes a non-volatile memory and a memory controller. The memory controller is configured to perform a write operation on the non-volatile memory in response to a write command from a host by writing system data in a first mode to a first block of the non-volatile memory, the first mode being a write mode for writing data with a first number of bits per memory cell, writing user data in the first mode to a second block of the non-volatile memory when the write command is of a first type, and writing user data in a second mode to a third block of the non-volatile memory when the write command is of a second type. The second mode is a write mode for writing data with a second number of bits larger than the first number of bits per memory cell.