<p>The supply voltage (VB) to a load (40) is interrupted at a predetermined rate by a switch (Sw1) to control the average load current. A capacitor (C1) is charged with a potential difference generated between the load (40) and power source during the periods in which the switching means (Sw1) is off, so that a control voltage exceeding the power supply voltage (VB) is supplied to a drive circuit (20) by using the charged voltage of the capacitor (C1). Therefore, a high-side switch using an N-type semiconductor element can be realized with a simple circuit.</p>
