In a two layer extrusion molding, a core part 11 is formed of hard resin material, a crease pattern 11a having a given depth, preferably, a depth in the range of 10 to 20 .mu.m is formed on the surface of the core part 11, and a skin part 12 formed of soft resin material is coated on the surface of the core part 11. Thus, the core part and skin part are effectively prevented from being detached from each other to thereby improving the quality of the molded product.