PURPOSE: To control the frequency of writing to a rewritable PROM easily and securely, by disposing a circuit which controls the frequency of writing and a general data storage circuit discretely on the same substrate.

CONSTITUTION: The writing and reading of the rewritable PROM (EEPROM) 3 are controlled through the 1st control part 1a. The frequency of the rewriting of the EEPROM3 is counted and stored by the 2nd control part 2a, counter 5, EEPROM7, etc., and compared by a comparing part 6a with the limit value of an ROM4a to control the rewriting frequency of the EEPROM3. The EEPROM3 including this general data storage circuit and a writing frequency control circuit including the control part 2a, counter 5, EEPROM7, ROM4a, comparing part 6a, etc., are disposed discretely on the same chip 10, and their outputs are sent out through different terminals. This constitution controls the rewriting frequency of the rewritable programmable ROM easily and securely.