To measure time over a wide dynamic range, with high stability and a high accuracy.

A standard clock synchronous to a trigonometric function wave of a sine wave and a cosine wave is generated at a standard pulse generation circuit 12. Two kinds of the trigonometric function waves are A/D converted by ADC 16, 18 with a timing of arrival of a start signal, and this value is subjected to inverse trigonometric function operation by an operation processing device 46 to calculate a micro time at a start side. A sine time at a stop side is also calculated similarly. A pulse is generated at an AND circuit 40 between synchronous start and stop signals taking a synchronism at FF 24, 38 and is counted by a scaler 42 and a count number at the time of stop is stored in a register. The operation processing device 46 calculates the overall measurement time using the count number, clock period time and two micro times.