PURPOSE: To facilitate meter inspecting service and to deal with an increase in time zone by simple constitution by sending a pulse signal from a measuring instrument to a time-zone classified conversion means, and integrating a conversion output based upon the switching and setting of a pulse conversion ratio in each time zone.

CONSTITUTION: The pulse conversion ratio in each time zone is read out of a memory part 14-2 under the command of a processing judgment part 14-3 and set in respective pulse converting circuits 13-1W13-n. When a circuit where a pulse conversion ratio corresponding to, for example, the current time is 13-1, only the circuit 13-1 receives a pulse signal from a pulse oscillator 11 with a switching signal from the judgment part 14-3 and generates a conversion output. This signal is sent to a pulse-charge converting circuit 15 and every time the number of input pulses reaches a specific value, charge is added to find the charge for use, which is displayed on a charge display circuit 16. Then, the pulse converting circuit is switched at intervals of time zones and the conversion to the charge is performed with the pulse signal similarly to facilitate meter inspecting service and a circuit 13-n is only connected additionally even when the time zone increases.