PURPOSE: To easily decide deterioration at every medium in addition to statistics information at every device by sampling statistics information of a peripheral device whenever the use of the medium terminates and editing statistics information at every medium.

CONSTITUTION: When an input output type decision means 13 receives the input/ output termination interruption of the peripheral device from a peripheral device controller 9, an idle buffer securing means 3 refers to a flag during the use from a statistics information buffer area 1, searches an idle statistics information buffer 2, turns on the flag during the use to secure it when it is decided that the medium is taken. A statistics information reading means 6 logs statistics information to a log buffer 8. When log is completed, a statistics information erasing means 5 clears the statistics information buffer 2, transfers control to an input/output termination means to terminate the processing. Thus, statistics information of the peripheral device 11 is sampled whenever the use of the medium terminates, and statistics information at every medium can be edited in addition to statistics information at every device, whereby the decision of the deterioration of the medium can easily be executed.