PURPOSE: To uniform the tension of a metallic foil, reduce vibration and carry out resin coating of uniform thickness by using a contour nipple and an air vacuum chamber in the process of extruding molten fluororesin together with metallic foil out of a die.

CONSTITUTION: A crosshead section 1 of an extruder is constituted of a molten fluororesin feeding section 2, a metallic foil feeding section 3 and a die 4. A contour nipple 5 is installed in the die 4 and an air vacuum chamber 6 is provided in the upstream side of the contour nipple 5. Metallic foil M is fed through a pinch roll 8, the air vacuum chamber 6, a metallic foil feeding section 3 and a contour nipple 5, and it is guided out of a die 4. Fluororesin F melted in the extruder goes through a feeding section 2, coating the metallic foil M in the die 4, and extruded. It is necessary to suck air from both sides of the metallic foil M in the air vacuum chamber 6, by which uniform tension is applied to the metallic foil M and vibration is prevented to coat the metallic foil with fluorine resin uniformly.