An A/D conversion circuit includes: a pulse transit circuit into which either a power supply or current source and also a pulse signal is input, and through which the pulse signal transits; a transit position detection section that detects a transit position of the pulse signal within the pulse transit circuit, and outputs data in accordance with the transit position; and a digital data creation section that, based on the data output by the transit position detection section, creates digital data that corresponds to the size of the power supply or current source. The pulse transit circuit is formed by a plurality of inverter circuits that are joined together in series, and the plurality of inverter circuits are formed by identical logical elements in which delay times between input signals and output signals change in accordance with the size of the power supply or current source. In the pulse transit circuit, a start-up signal that causes the transiting of the pulse signal to commence is input into one of the plurality of inverter circuits, and the transit position detection section detects the transit position of the pulse signal within the pulse transit circuit based on the output signals from each one of the plurality of inverter circuits.