PURPOSE: To enable measuring quantity of variation of plural input signals precisely and simultaneously by providing plural switching means in which input signals are switched by arbitrary phases and arbitrary periods set by plural setting signal generation means on the basis of the prescribed signal and outputted.

CONSTITUTION: A sampling waveform detecting device 1 inputs a pulse generator signal S1 to an inversion circuit 2, and inputs an inverted pulse generator signal S2 to gate circuits 3-5 respectively. The circuits 3-5 give gated signals S3-S5 setting a detection part of high frequency sampled waveform based on the pulse generator signal S1 to switching circuits 6-8. The detection part of the high frequency sampled waveform is arbitrarily set by adjusting variable resistors of the gating circuits 3-5. A regenerated high frequency signal S6 is inputted to the circuits 6-8, the circuits 6-8 start to detect the regenerated high frequency signal S6 at arbitrary phases in accordance with the gated signals S3-S5, and output detected signals S7-S9 passed through for arbitrary periods.