PURPOSE: To reduce the labor of die replacing work by enabling the replacement only of a die, by constituting a preform die in a fixable manner corresponding to extrusion work.

CONSTITUTION: A die holding stand 30 for mounting dies 20 consisting of a preform die 21, a die 22 and a die holder 23 ina freely slidable manner is arranged to the lower part of the emitting port 12 of an extruder head 11. A pair of left and right clamp apparatuses 60 of the preform die 21 are provided to both sides of the head 11 in such a state that the preform die 21 is left and only the die 22 is made replaceable. A joint is connected to one end of the die holder 23 through a pin and the rod of the transfer means 31 such as the hydraulic cylinder arranged to one side part of the die holding stand 30 is connected to the joint. Further, a cutter apparatus 40 for removing a residual material is provided to the die holding stand 30.