A method of manufacturing a multilayer wiring board is disclosed, the method being capable of separating a substrate without large local warpage of the multilayer wiring layer and thereby improving the reliability of connection in the multilayer wiring layer. This method includes providing a laminated sheet having, in sequence, a substrate, a first release layer and a metal layer; forming a first wiring layer on the metal layer; alternately stacking insulating layers and wiring layers on the laminated sheet on which the first wiring layer is formed to give a laminate provided with a multilayer wiring layer; stacking a reinforcing sheet on the laminate provided with the multilayer wiring layer while interposing a second release layer; separating the substrate from the metal layer; and separating the reinforcing sheet from the laminate provided with the multilayer wiring layer to give the multilayer wiring board.