Provided is a non-volatile storage system that performs error correction processing at high speed while ensuring error correction capability. When error correction decoding processing using data read first with hard-decision decoding processing has failed, a non-volatile storage device 2 reads data on the same page again, performs diversity synthesis processing on the readout data for the first time and the readout data for the second time on the same page as one for the first time, and then performs error correction processing using data after diversity synthesis processing.