To prevent data preserved inside a flash memory from being stolen, corrected or changed by randomly combining the data and making the data of a non-transmission restoration process useless.

Blocking is advanced by a program preserved inside the flash memory, rotation is advanced on the basis of the blocks, a preserved address is scrambled and the data inside an original address are preserved inside a new address after the rotation. At the time of reading the data, the read order of a random number is generated by a random number generator and accurate data and dummy data are included in the read data. The dummy read data are filtered, address rotation is recovered and restored and they are turned to original data. By scrambling the address, the data are turned to the useless data when they are directly read.