PURPOSE: To obtain highly accurate control display by only mechanical processing at a comparatively low cost by providing an arithmetic memory to temporarily store detection information related to the operating conditions of printer under a counting condition and to counter pulse related to printing paper and a means to print out control information for every operation unit at necessary time.

CONSTITUTION: A starting and stopping sensor 1 jointly using the power source switch of printer, an operation start sensor 2 jointly using the main operating switch, an operation end sensor 3 jointly using a rod ending switch, and a feeding sensor 4 jointly using a sheet counter set on the paper supply port of the printer are provided. Pulse signals from a print-out sensor 5 is put through an interface 6 into a simple computer 8 with a clock unit 7 to judge and store start and stop times, operation start time, and operation end time as well as to count and store the number of print-out papers and of feed-out papers. When sending out stored values by the printer 9 by read-out signals at necessary time, the lapse of the times is calculated and the resulting elapsed time and paper number-differential calculated values are printed out concurrently.