<p>A first and a second transistors coupled in series by connecting the collector of the first one (26) to the emitter of the second one (30) are connected at the collector of the second transistor through a resistor to a first power source (VCC21) of a voltage as high as about two times the breakdown voltage of these transistors, a third transistor (29) is coupled at the collector to the base of the second transistor and a second power source (VCC32) of the lower voltage than the first power source through a load resistor, and the base of the third transistor is connected to the base of the first transistor; whereby an output voltage of the second transistor (V22) is divided into the respective collector-emitter voltages of the first and second transistors, and the output voltage exceeding the breakdown voltage of the transistor is obtainable.</p>