A process for producing a circuit board includes the steps of etching the third metal layer of a three-layer metal laminate into a predetermined interconnection pattern by photolithography; forming a laminate on the interconnection pattern by a buildup method, the laminate including interconnection patterns with insulating layers provided therebetween, the interconnection patterns being electrically connected to each other; separating a first metal layer from a supporting substrate to detach the laminate; removing the first metal layer of the three-layer metal laminate by etching using a second metal layer as a barrier layer; and removing the exposed second metal layer by etching.