the present invention feeds a plurality of different molten resin jet streams into a t die adapted to produce film members such as plastic films . a plurality of molten jet streams extruded from a plurality of extruders , respectively , are fed from their predetermined directions into one resin feed passage in communication with the t die and combined or united without causing the mixture with each other . the relative positional relationship between the intersurfaces between the adjacent molten resin jet streams defined when the molten resin jet streams are combined or united on the one hand and an elongated discharge port of the t die can be adjusted so that the relative positional relationship between a plurality of extruders and the t die can be freely changed .