PURPOSE: To improve the responsivity of the indication of measurement, the precision of measurement and the stability thereof in the region of low dose rate and to unncessitate the ajustment of the device by using an up-down counter and indicating the figure signal of the output thereof as the counting rate of an input pulse.

CONSTITUTION: An input pulse whose counting rate is to be measured is supplied to the up input terminal of the up-down counter 1 and each figure signal obtained from the counter 1 is supplied to each figure controlling terminal of a rate multiplier 2. Furthermore, a pulse-train signal N with a prescribed repeated frequency is supplied to the clock inout terminal of the multiplier 2, while the output of the multiplier 2 is supplied to the down input terminal of the counter 1, and each figure signal is indicated 3 as the counting rate of the input pulse. In addition, by adding time-constant circuits which can be shifted to between the input and the counter 1 and between the output of the multiplier and the counter l, respectively, the counting rate can be indicated in a direct reading manner.