Abstract: Provided is a method for manufacturing a case for a portable electronic device. The method includes: adhesive applying for applying an adhesive to a back side of a sliced veneer sheet; reinforcing strengthener attaching for attaching a reinforcing strengthener, which has a higher tensile and rupture strength than the sliced veneer sheet, to the back side of the sliced veneer sheet, so as to reinforce a strength of a sliced veneer; elastic layer forming for providing an elastic layer, which is made of a more elastic material than the sliced veneer sheet, to a surface of the reinforcing strengthener so as to provide elasticity to the sliced veneer sheet; and injection molding for injection-molding a case body that is formed of a synthetic resin material to cover at least one side of the portable electronic device, by inserting the sliced veneer sheet, the reinforcing strengthener, and the elastic layer into a mold.