A molded body formed with pulp mold having projected lines corresponding to a slit-shaped vent package part, capable of being provided by paper-making/dewatering, using a paper making mold, a slurry having fibers dispersed in a liquid so as to obtain a three-dimensional fiber wetted laminated body, moving the laminated body to a dry mold having an inner surface with the slit-shaped vent package, and pressing and drying that laminated body.