To solve an actual problem wherein a practical propeller diameter variable device is not seen in the market though it is known that efficiency of a propeller is improved when a diameter of a blade is enlarged while there is a windmill for a ship, an aircraft, and wind power generation using thrust of the propeller as a machine using the rotating propeller, and there are a washer, a domestic and industrial material mixing mixer, and a cutter as a mixing machine using the propeller.

An increase in propulsion of the propeller, an improvement in an energy-saving effect, an agitating effect, and the working efficiency, and an improvement in quality are expected by changing a pitch and a diameter of the propeller.