To measure a counting rate by removing noise to prevent erroneous counting due to noise.

A counting rate is measured by normal measuring means with a feedback type counting rate meter comprising an up/down counter 1, a pulse generator 2 and a calculator 3. A counter 4 counts a measured pulse at a predetermined sampling frequency, and if a current count value exceeds the upper limit of tolerance compared to a previous count value, the counting rate just before that exceeding is assumed as a counting rate to be found, and if it is within the tolerance, the counting rate is found by a re-tray calculation which calculates the counting rate for correction, and after it exceeds the upper limit of tolerance for a predetermined continuous period, measurement is done by normal measuring means. When it is within the tolerance or after re-try calculation, the counting rate is found, based on the comparison result with current count value.