An electric tool may include an electric motor, a spindle to which a working tool may be attached, and a torque transmission path provided between the electric motor and the spindle and including a first rotary member and a second rotary member. The current sink is coupled to the photoflash diode for controlling the current through the photoflash diode. A negative electrode 6b is formed at the apex on the opposite side to the positive electrode, and an antireflection film is formed on the surface side of the diffusion layer.