The extruding apparatus has the molding die to form the ceramic molding, the screw extruder containing the extrusion screw to knead and guide the ceramic material toward the molding die. The extrusion screw is comprised of the pressure screw part and the diffusion screw part. The diffusion screw part provided at the front end of the extrusion screw has a diameter greater than the screw diameter of the pressure screw part.