The integrated circuit device includes: an electrostatic protection circuit that is provided between first and second power supply lines coupled to external terminals respectively, and forms a current pathway between the first and second power supply lines during a given period in response to an increase in a voltage between the first and second power supply lines; and a power supply generating circuit that performs power supply control based on a voltage of the first power supply line and generates a control signal in accordance with a switching timing of the power supply control. And, the electrostatic protection circuit includes an adjustment circuit for shortening the given period in response to the control signal.