PURPOSE: To enable operations from the user of a computer with the same process as a conventional auxiliary storage device, to improve speed for writing and reading data, to eliminate noise or vibrations and further to reduce energy consumption.

CONSTITUTION: When a computer 1 outputs the request of writing or reading data, the request is reported through an interface 2 to a semiconductor storage medium control part 3. The semiconductor storage medium control part 3 converts the received request from a request to control the conventional auxiliary storage device to a request to enable the control of a semiconductor element and executes write and read to a semiconductor storage medium 4. Semiconductor storage media A32 and B33 can be exchanged similarly to floppy disks A22 and B23, and the floppy disk device and the auxiliary storage device using the semiconductor element are equally handled from the user.