Charged particle beam device and charged particle beam measurement method

Accuracy in the measurement of the amount of secondary electrons released, and stability of charged particle beam images are achieved simultaneously in a charged particle beam device. In the charged particle beam device, extraction of a detection signal is started by a first trigger signal, the extraction of the detection signal is terminated by a second trigger signal, the detection signal is sampled N times (N is a natural number) by N third trigger signals dividing equally a time interval T between the first trigger signal and the second trigger signal, and the second order charged particles are measured by integrating and averaging the signals sampled within each of the time divisions ΔT resulting from an equal division of the time interval T, the time divisions ΔT being controlled in such a way that the number of second order charged particles measured is greater than the minimum number of charged particles to satisfy ergodicity.