An LED illumination dimming circuit comprises a capacitor connected to the first output terminal at a first end thereof and to the second output terminal at a second end thereof; a coil connected to the second end of the capacitor at a first end thereof; a switch element connected to a second end of the coil at a first end thereof; a resistor connected to a second end of the switch element at a first end thereof and to the ground terminal at a second end thereof; a diode connected to the power supply terminal at a cathode thereof and to the second end of the coil at an anode thereof; and a controlling circuit that controls an operation of the switch element with a switch controlling signal.