An electrostatic discharge protection element and a protection resistor, which are formed on an N− drain region with a field oxide film interposed therebetween for the purpose of preventing electrical breakdown of a field effect transistor, are composed as a stacked bidirectional Zener diode of one or a plurality of N+ polycrystalline silicon regions of a first layer and a P+ polycrystalline silicon region of a second layer, and a stacked resistor of one or a plurality of N+ resistor layers of the first layer and an N+ resistor layer of the second layer, respectively. One end of the plurality of N+ polycrystalline silicon regions of the first layer is connected to an external gate electrode terminal, and the other end is connected to a source electrode. One end of the plurality of N+ resistor layers of the first layer is connected to a gate electrode, and the other end is connected to the external gate electrode terminal. Semiconductor regions of the first layer and the second layer are formed by using semiconductor films, which form a hetero semiconductor region and the gate electrode, respectively.