A charging device for charging an electric vehicle includes a power plug, a charging gun, a control box, a temperature detecting circuit and an over-temperature protection circuit. The charging gun is detachably connected with the electric vehicle and includes a connection confirmation terminal and a connection confirmation circuit. The connection confirmation circuit outputs a connection confirmation signal to the connection confirmation terminal. The temperature detecting circuit detects the temperature of the power plug or the control box and outputs a temperature signal to a second control unit of the control box when the temperature of the power plug or the control box exceeds a threshold temperature level. The over-temperature protection circuit is electrically connected between the second control unit and the connection confirmation terminal. The second control unit controls the over-temperature protection circuit to adjust the voltage level of the connection confirmation terminal according to the temperature signal.