A time to digital converter has a counter, a first phase difference detector, a first capacitor, a second capacitor having capacitance N times a capacitance of the first capacitor, a comparator to compare a charge voltage of the first capacitor with a charge voltage of the second capacitor, a first charge controller, a first phase difference arithmetic unit, a second phase difference detector, a second charge controller, a second phase difference arithmetic unit to operate the phase difference between the first signal and the second signal, and a third phase difference arithmetic unit to detect a fractional phase difference between the first signal and the second signal. The first phase difference arithmetic unit operates the phase difference between the first signal and the second signal, based on a reference phase, when the counter suspends a measurement operation.