Periodic signal measuring device, periodic signal measuring method and sampling period determining method including a measuring section, a sampling period determining section, and a sampling period control section

The invention relates to a periodic signal measuring device, a periodic signal measuring method and a sampling period determining method. On the one hand, the increase on the processing loads and costs is suppressed. On the other hand, the measurement error of the periodic signal is suppressed. The periodic signal measuring device of the present invention includes: a measuring section 1 that samples the periodic signal S and performs a predetermined process on the sampled value, thereby obtaining a measured value M; a sampling period determining section 3 that determines the sampling period of the measuring section 1 in a way that the amount of deviation of the measured value M within a certain measurement period is within the allowable range; and a sampling period control section 4 that sets the sampling period of the measuring section 1 based on the determination by the sampling period determining section 3.