PURPOSE: To obtain a mixing and homogenizing extruder wherein high processing ratio is possible by a little invested capital and the same good mixing action in comparison with a well known apparatus.

CONSTITUTION: An extruder 1 provided with two successively arranged mixing range and homogenizing range 7 and 8 and the first range is formed as a pin- cylinder range 7 and another range is formed as a transfer range and in the screw 6 of the extruder, the channel vol. is always decreased to zero and the channel vol. is increased to the max. value from the inlet range to the outlet range and successively, to decrease the channel vol. to zero, the housing 2 of the extruder is provided with an interrupted housing channel wherein the channel vol. is increased from zero to the max. up to the outlet range of a transfer part.