A rotary type electrostatic spray painting device including a rotary shaft driven by an air turbine. A reflecting face portion and a non-reflecting face portion are formed on the rear end face of the rotary shaft. A rotating speed sensor is arranged adjacent to the rear end face of the rotary shaft to detect the rotating speed of the rotary shaft from light reflected from the reflecting face portion. The amount of pressurized air fed into the air turbine is controlled in response to the output signal of the rotating speed sensor so that the rotating speed of the rotary shaft becomes equal to a desired rotating speed.