The sealed kneading machine of the present invention is provided with a kneading chamber to which a material to be kneaded is supplied, and a rotor disposed in the kneading chamber so as to be able to rotate about a rotor shaft. The rotor is provided with a plurality of kneading blades for kneading the material to be kneaded, and the length of all the kneading blades in the rotor shaft direction of each thereof is 45% or less of the total length of the rotor in the rotor shaft direction.
