PURPOSE: To permit arbitrary reading/writing of corresponding information from and into a storage device by inputting the instruction codes of reading/writing by means of ten-keys or the like.

CONSTITUTION: If various sets of information such as number of copying sheets, date of inspection, date of replacement of cosumables and the like necessary for maintenance of a copying machine are stored beforehand in an RAM36, and the instruction codes of reading/writing from and into the RAM63 from ten- keys 8 are inputted, a CPU44 performs reading/writing of the information corresponding to the instruction codes from and into the RAM63.