Apply heat to thermoplastic resin film, which is eventually to become an insulating resin layer, and press the film against a mold for forming grooves on a surface of the film. Next, press-fit an electronic component into the resin film from a back-face of the film, thereby exposing electrodes of the component from a bottom of the grooves. Then cool the film for curing. Peel the film off the mold, then fill the grooves with conductive paste, and cure the paste for forming circuit patterns. The foregoing procedure allows bringing the electrodes positively into conduction with the circuit patterns of a circuit board incorporating the electronic component, and achieving a narrower pitch between routings of the circuit patterns.