An electrical stimulation device is provided. The electrical stimulation device includes a boost circuit, a voltage selecting circuit and a control circuit. The boost circuit generates a plurality of voltages, wherein the voltages have different voltage values. The voltage selecting circuit is coupled to the boost circuit and selects one voltage according to a reference voltage on a tissue impedance to generate an output voltage. The control circuit is coupled to the boost circuit and in response to electrical stimulation; it transmits a control signal to enable the boost circuit.