PURPOSE: To obtain an improved method for extruding a composite containing layers or layer surfaces having thermally distinct processing requirements by introducing two flows different in temp. into an extruder having thermally independent flow channels and allowing them to meet with each other.

CONSTITUTION: A die main body 12 having a manifold 14 and the front land flow channel 16 provided on the downstream side thereof to fluidally communicate with an outlet orifice or slot 18 by a land flow channel 20 are provided. The cross-sectional height of the front land flow channel and the land flow channel to the manifold restricts a main flow direction to generate a lateral flow in the manifold. Side flow channels 22, 24 communicate with the manifold fluidally at the upstream part of the manifold and are provided in die main body halves 12A, 12B pref. in a thermally independent manner.