To attain preventive maintenance by substituting an article to be periodically substituted at suitable time.

When a user turns on a power supply switch 11 on a control board 1 for an information processor, power is supplied to the processor and a timer 2 starts to count up time and outputs counted time to an integrator 3 at every 10min e.g. At the time of turning on the switch 11, the integrator 3 reads out cummulative energization time cummulated up to the preceding power supply from a non-volatile memory 4 and adds a count value to the read cummulative energization time at every 10min e.g. to update the contents of the memory 4. Thereby the contents of the memory 4 indicate the cummulative energization time cummulated up to current time every 10min unit. When the user turns on a display switch 13 on the board 1, a display control part 5 reads out the contents of the memory 4 and displays the cummulative time information on a digital display device 12.