In a method of manufacturing a wiring substrate of the present invention, first, a structure in which an underlying layer is arranged in a wiring forming area of a temporary substrate and a peelable multi-layer
metal foil that is larger in size than the underlying layer is arranged on the underlying layer and is adhered partially to an outer
peripheral portion of the wiring forming area of the temporary substrate, and the peelable multi-layer
metal foil is constructed by temporary adhering a first
metal foil and a second
metal foil with peelable. Then, a built-up wiring layer is formed on the peelable multi-layer
metal foil, and the peelable multi-layer
metal foil is separated from the temporary substrate by
cutting a portion of such a structure that the underlying layer, the peelable multi-layer metal foil, and the built-up wiring layer are formed on the temporary substrate, the portion corresponding to a
peripheral portion the underlying layer, whereby a wiring member in which the built-up wiring layer is formed on the peelable multi-layer metal foil is obtained.