An extrusion head device in which fixed and movable head parts as a plurality of separate parts can be easily combined using compact fastening means. Fastening cylinder rods provided for the fixed head part of the extrusion head device including the fixed and movable head parts are expanded, whereby fore-end locking portions at tips of the fastening cylinder rods are inserted into through holes of engaging blocks provided for the movable head to be protruded from upper surfaces of the engaging blocks; stopper-operating cylinder rods provided for the movable head part are expanded, whereby U-shaped stoppers at tips of the stopper-operating cylinder rods are inserted into clearances between the locking portions and the engaging blocks; and then the fastening cylinder rods are contracted, whereby the movable and fixed head parts are brought into tight contact with each other and fastened together.