with reference to fig1 through fig1 the method for fabricating a circuit device according to the invention is comprised of the steps of preparing an insulation resin sheet having the surface of a conductive layer overcoated with insulation resin forming through holes in the above described insulation resin at appointed points on the above described insulation resin sheet and selectively exposing the rear side of the above described conductive layer forming a conductive plated layer in the above described through holes and on the surface of the above described insulation resin forming a first conductive path layer by etching the above described conductive plated layer to an appointed pattern adhering and fixing semiconductor elements on the above described first conductive path layer with the same electrically insulated therefrom overcoating the above described first conductive path layer and the above described semiconductor elements with a sealing resin layer forming a second conductive path layer by etching the above described second conductive layer to an appointed pattern and forming external electrodes at appointed points of the above described second conductive path layers the first step according to the invention prepares as shown in fig1 an insulation resin sheet 1 having the surface of a conductive layer 3 overcoated with insulation resin 2 the insulation resin sheet 1 is formed by overcoating the entire surface of the conductive layer 3 with the insulation resin 2 the material of the insulation resin 2 is an insulation material made of macromolecules such as polyimide resin or epoxy resin etc also the conductive layer 3 is preferably mainly composed of cu or may be a material of.