PURPOSE: To provide a press forming die which can be economically produced with lightness in weight by combining plural pieces of vertical and horizontal flat plates spaced from each other, inserting the assembly in a molding frame, filling a packing material in the spaces partitioned by the flat plates and forming a pressing surface.

CONSTITUTION: Plural pieces of vertical and horizontal flat plates 5, 6 are coupled into a grating shape in which the flat plates spaced at a prescribed distance intersect orthogohally with each other to form a die body 1 which is inserted into a molding frame 2 attached on a bottom plate 10. A packing material 3 is filled in the spaces 11 partitioned by the plates 5, 6. A composite material of the characteristic which is moderably semi-fluid and creamy for the beginning of filling and solidifies after a specified time to the hardness withstanding cutting, polishing, etc. and suitable for pressing operation, for example, a material prepd. by kneading together PE and glass fibers is used for the material 3. The end faces 12, 13 of the plates 5, 6 of the body 1 and the surface of the material 3 are further molded to a prescribed shape to provide a pressing surface 4. A top mold and a bottom mold having a pair of the male and female surfaces 4 are thus produced.