A non-volatile storage device control method capable of normally performing write upon start after a failure such as power cut-off has occurred during data write or erase and the processing has been interrupted. The non-volatile storage device control method includes: a first flag write step for writing a fixed value indicating that data is written in a first flag existing in a redundant area of a head page of a physical block and indicating whether the head page contains written data when writing data in a non-volatile memory consisting of a plurality of physical blocks, and a data write step for writing data in the physical block.