An A/D converter has a pulse delay circuit including a plurality of inverting circuits to each of which an analog voltage signal is inputted through a first pair of power supply lines. Each of the inverting circuits has a first logic gate. The A/D converter has a logic circuit having a second logic gate and a second pair of power supply lines, the logic circuit operating based on a power supply voltage. At least one of a first range of a level of the voltage signal and a second range of the power supply voltage is set to prevent a tunneling current from flowing at least one of between the first paired power supply lines and between the second paired power supply lines when at least one of first and second logic gates operates.