In an electric tool, in order to carry out a phase control or an antiphase control using a transistor, constant voltage generating means of the tool includes a series circuit including a resistor and a diode, and a parallel circuit including a capacitor and a Zener diode. One end of the resistor is connected between an AC power supply and an AC motor. A cathode of the diode is connected to one capacitor end and a cathode of the Zener diode. The other capacitor end and an anode of the Zener diode are connected to transistor sources. One ends of resistors are connected to gates of the transistors, and a voltage at the other ends of the resistors are switched between a voltage at a node between the series circuit and the parallel circuit and a voltage of the source of the transistors to turn the transistors ON or OFF.