An electrostatic discharge protection device including a PNP transistor, a protection circuit and an adjustment circuit is provided. An emitter of the PNP transistor is electrically connected to a pad, and a collector of the PNP transistor is electrically connected to a ground. The protection circuit is electrically connected between a base of the PNP transistor and the ground, and provides a discharge path. When an electrostatic signal occurs on the pad, the electrostatic signal is conducted to the ground through the discharge path and the PNP transistor. The adjustment circuit is electrically connected between the emitter and the base of the PNP transistor. When a power voltage is supplied to the pad, the adjustment circuit provides a control voltage to the base of the PNP transistor according to the power voltage, so as to prevent the emitter and the base of the PNP transistor from being forward biased.