An extrusion molding apparatus comprises a shaping die for producing a ceramic molded product, and a screw extruder having built therein an extruding screw (40) for mixing while leading a ceramic material forward. The extruding screw (40) includes a pressing screw portion (410) having a first lead (411) and a dispersing screw portion (420) having a second lead (421) adjacent to a forward end (412) of the pressing screw portion (410). The second lead (421) is formed in such a manner that the rear ends of all the second lead surfaces (426) at the rear end (422) of the dispersing screw portion (420) and the forward end of the first lead surface (416) at the forward end (412) of the pressing screw portion (410) are displaced from each other.