A kneading extruder comprising: a barrel including a first raw material supply port through which first raw material is supplied, a second raw material supply port through which second liquid raw material is supplied and a barrel extrusion port through which kneaded material including the first raw material and the second raw material in a melted state is extruded from inside of the barrel, the second raw material supply port being located downstream of the first raw material supply port, a screw shaft placed in the barrel, the screw shaft kneading the first raw material and the second raw material to produce the kneaded material in the melted state, a screw driving device providing a rotary movement of the screw shaft at a constant speed, a die communicating with the barrel extrusion port, the die having a die extrusion port through which the kneaded material in pressurized state extruded through the barrel extrusion port, is extruded to outside of the kneading extruder(1, 101, 201, 301), a booster pump for boosting the pressure of the kneaded material, the booster pump being located between the barrel extrusion port and the die, and the booster pump being continuously driven at a constant speed, a first gear pump for ejecting a portion of the kneaded material extruded through the barrel extrusion port, the first gear pump being located between the barrel extrusion port and the booster pump, a first pressure detection unit for detecting pressure of the kneaded material that is provided at the barrel extrusion port, first ejection quantity regulating means for changing the number of rotations of the first gear pump to regulate a quantity of the portion of the kneaded material ejected by the first gear pump such that the pressure detected by the first pressure detection unit is kept constant, a second gear pump for ejecting a portion of the kneaded material supplied into the die, a second pressure detection unit for detecting pressure of the kneaded material at the die extrusion port, and second ejection quantity regulating means for changing the number of rotations of the second gear pump to regulate a quantity of the portion of the kneaded material ejected by the second gear pump such that the pressure detected by the second pressure detection unit is kept constant. a barrel including a first raw material supply port through which first raw material is supplied, a second raw material supply port through which second liquid raw material is supplied and a barrel extrusion port through which kneaded material including the first raw material and the second raw material in a melted state is extruded from inside of the barrel, the second raw material supply port being located downstream of the first raw material supply port, a screw shaft placed in the barrel, the screw shaft kneading the first raw material and the second raw material to produce the kneaded material in the melted state, a screw driving device providing a rotary movement of the screw shaft at a constant speed, a die communicating with the barrel extrusion port, the die having a die extrusion port through which the kneaded material in pressurized state extruded through the barrel extrusion port, is extruded to outside of the kneading extruder(1, 101, 201, 301), a booster pump for boosting the pressure of the kneaded material, the booster pump being located between the barrel extrusion port and the die, and the booster pump being continuously driven at a constant speed, a first gear pump for ejecting a portion of the kneaded material extruded through the barrel extrusion port, the first gear pump being located between the barrel extrusion port and the booster pump, a first pressure detection unit for detecting pressure of the kneaded material that is provided at the barrel extrusion port, first ejection quantity regulating means for changing the number of rotations of the first gear pump to regulate a quantity of the portion of the kneaded material ejected by the first gear pump such that the pressure detected by the first pressure detection unit is kept constant, a second gear pump for ejecting a portion of the kneaded material supplied into the die, a second pressure detection unit for detecting pressure of the kneaded material at the die extrusion port, and second ejection quantity regulating means for changing the number of rotations of the second gear pump to regulate a quantity of the portion of the kneaded material ejected by the second gear pump such that the pressure detected by the second pressure detection unit is kept constant.