A die head is provided with a plunger and a measuring chamber, and the molten resin is uniformly fed to the die head of an extrusion-forming machine. That is, the die head comprises a main layer-forming flow passage for flowing a molten resin into an ejection port of the die head of the extrusion-forming machine passing through the die head, and a core layer-forming flow passage for intermittently flowing a molten resin into the ejection port of the die head passing through the die head. The main layer-forming flow passage and the core layer-forming flow passage are provided with measuring chambers into which the molten resins are pressure-introduced from the upstream sides of the flow passages due to the pressure-feeding forces of the molten resins, and the measuring chambers are provided with plungers which move back due to the pressure-feeding forces of the molten resins and eject the measured molten resins to the downstream side of the flow passage, and the amounts of ejecting the molten resins by said plungers and the ejection timings are controlled by control units that control the plungers.