A method for manufacturing a wiring substrate that includes: providing a laminated sheet that includes a release layer and a metal layer in order on a carrier; forming a cut from a surface of the laminated sheet opposite to the carrier so that the cut passes through the inside of an outer edge portion of the laminated sheet and so that the cut penetrates the metal layer and the release layer, and dividing the metal layer and the release layer into a central portion and a peripheral portion with the cut as a boundary; and inserting a thin piece from the cut toward the central portion side of the metal layer or the release layer to form a gap between the metal layer and the carrier in which an insertion angle of the thin piece is greater than 0°.