PURPOSE: To eliminate the need of an elimination operation at the time of write by providing an elimination management means for managing the elimination part of two flash type EEPROMs and a simultaneous function execution means.

CONSTITUTION: The flash type EEPROM 5 and the function selection circuit 15 of this semiconductor file device 1 for reading and writing data to/from the flash type EEPROM 5 by the control of a host controller 2 are duplexed and an elimination block management circuit 14 is provided. Then, an access control circuit 4 selects a read circuit 10 by using the function selection circuit 15(A), transfers a block provided with the data to be rewritten of the flash type EEPROM 5(A) to a work memory 7 by using the read circuit 10 and writes the contents of a data register 6 in a work area by referring to an address register 8. Then, an elimination circuit 11 and a write circuit 12 are selected, the contents of the work memory 7 are written in the flash type EEPROM 5(B) and simultaneously, the data of the block read from the flash type EEPROM 5(A) are eliminated.