PROBLEM TO BE SOLVED: To prevent gelation from occurring and to uniformly mix a photo-sensitive resin compsn. by a method wherein the photo-sensitive resin compsn. is fed into a uniaxial extruder in which a screw with a flight with a cutting is rotated in a barrel provided with a pin while it is moved forward and backward and after the compsn. is mixed, it is extruded into a flat face from a wide slit nozzle. SOLUTION: A photo-sensitive resin compsn. is fed into a uniaxial extruder in which a screw 1 with a flight 4 with a cutting is rotated in a barrel 3 provided with a pin 2 while it is moved forward and backward. After the compsn. is mixed, it is extruded into a flat face from a wide slit nozzle and it is furthermore rolled by means of a calender roll. In this case, in a co-kneader, as an intermittent screw 1 (a screw with a flight) moves around so as to sew through kneading pins 2, the screw is cleaned and the resin is extruded without retention. In addition, distribution and mixing action for solid ingredients and liq. ingredients are very high by the action of the pins and the intermittent screw and mixing is uniformly performed thereby without local heat generation.