PURPOSE: To improve the measurement precision by counting cycles of a 1st and a 2nd signal an integral number of times in a measurement cycle, and outputting a signal showing the deviation of their time interval as a signal representing the value of a physical parameter.

CONSTITUTION: The transducers which output rectangular waves S1 and S2, which have frequencies F1 and F2 and cycles T1 and T2, are composed of resonators 6 and 8 and additional circuits 12 and 14, and the essential part of a processing circuit 16 is composed of count means 18 and 20 and a logic circuit 22. Then a means 18 counts cycles T1 of the signal S1 from the circuit 12 and a means 20 counts cycles T2 of the signal S2 from the circuit 14 with an integer N2; and a signal Sm representing a quantity equal to the time interval N1T1-N2T2 is outputted according to the time from the count start to the count end.