To eliminate a gear pump by obtaining an enough discharge pressure by increasing the diameter of the discharge screw of screws to be equivalent to the diameters of the other parts and bringing them into an engaged state.

A kneading adjusting apparatus for a twin-screw extruder is composed of two screws (30) which are arranged to be rotatable in an engaged state and to be parallel in a parallel state, a cylinder (20) in which a through inner hole into which each screw (30) can be inserted is formed, each conical hole (28) corresponding to the taper fitting (36) of each screw (30), a kneading adjusting plate (27) which makes the taper fitting (36) penetrate the conical hole (28) concentrically and is inserted into the through inner hole of the cylinder (20) to cross it, and a kneading adjusting driving apparatus which makes the cylinder reciprocate in the axial direction in relation to the screws (30).