A memory controller specifies, from a nonvolatile memory, a final page candidate, which is a candidate to be the physical page to which data is last written in a logical block. The memory controller executes an upward check process to determine whether the number of programmed physical pages is among a first range number of physical pages in a reverse order from the final page candidate is equal to or greater than a first reference value. The memory controller executes a downward check process determining whether the number of programmed physical pages is among a second range number of physical pages existing in the downward order from the final page candidate is equal to or less than a second reference value, and specifies the physical page to which data is last written in the logical block from results of the upward check process and the downward check process.