In a TAD (Time Analog-to-Digital) type of A/D converter in which delay units of a pulse delay circuit successively transfer a pulse signal during each of successive measurement intervals, with each delay unit applying an amount of delay determined by an analog input signal voltage, it is ensured that each new measurement interval begins as soon as the pulse delay circuit has become restored to an initialized condition after the preceding measurement interval. Output values expressing the number of delay units traversed by the pulse signal during a measurement interval are used directly as digital values representing the analog input signal voltage level.