An EPROM integrated circuit (20) includes a plurality of banks. When a data write operation is to be performed for this EEPROM integrated circuit (20), a bank which is used once is not used again, but the operation is constantly performed for new banks. In order to select a bank, a write number storage area (21) is provided in the EPROM integrated circuit (20), and the contents of the write number storage area (21) are updated by a write number updating circuit (29) each time the write operation is performed for a new bank.