To provide an oscillator or the like that outputs a clock signal to an outside and determines information indicating a relationship between the clock signal and an external signal.SOLUTION: An oscillator 10 includes a vibrator XTAL, a clock signal generation circuit 110, a terminal TQP, a terminal TIP, and a time digital conversion circuit 120. The clock signal generation circuit 110 oscillates the vibrator XTAL and generates a clock signal CLK. The terminal TQP outputs the clock signal CLK. The terminal TIP receives input of an external signal EXIN. The time digital conversion circuit 120 measures a time difference between transition timing of a first signal based on the external signal EXIN and transition timing of a second signal based on the clock signal CLK and determines time difference information TMD corresponding to the time difference.SELECTED DRAWING: Figure 1