To sufficiently prolong a service life in updating the number of times of rewriting without limiting memory regions to be used as a counter.

A data conversion unit 34-1 divides data to be written to, for example, a non-volatile memory 32 having a limited number of times of rewriting including the erasure of a memory device into divided write data having a predetermined bit width and converts each of the divided write data to conversion data in which the update frequency from bit 0 to bit 1 when incrementing or decrementing is performed is approximately equal among respective bit positions. A data reverse conversion unit 34-2 decompresses the data read from the non-volatile memory 32 into divided read data having the predetermined bit width and subjects each of the divided read data to conversion opposite to the conversion of the data conversion unit so as to restore the data to its original data.