In an A/D converter, three capacitors are connected to a comparator. The A/D converter also includes three switching circuits that each input a first reference voltage, a second reference voltage, and a third reference voltage in the three capacitors. A control circuit selects at least two of the three switching circuits during a charging period of stray capacitance of each of the capacitors. The control circuit turns on one of the switching devices in the selected switching circuits simultaneously, and during a comparing period by the comparator, selects one of the three capacitors for each comparison, and selects another capacitor in the next comparison.