PURPOSE: To surely erase/write the information of a fixed storage device and to shorten time for developing a software by electrically erasing/rewriting information at the fixed storage device built in a control means and building an input/output control part in the control means.

CONSTITUTION: When an information input means 1 and a control means 2 are connected by cables 7-9, the information from the information input means 1 is written through an input/output control part 4 built in the control means 2 to a fixed storage device 3 similarly built in the control means 2. When reloading the information of the fixed storage device 3 after writing the information in the fixed storage device 3, fitting the control means 2 to a real machine and operating the real machine, the fixed storage device 3 can surely erase and rewrite the information in the fixed storage device 3 according to an electric signal from the information input means 1 without detaching the control means from the real machine by connecting the information input means 1 and the control means 2 by the cables 7-9.