A supporting member or first synthetic resin sheet with conductive bumps disposed at predetermined positions are superposed on a second synthetic resin sheet under the condition that the resin component of the second synthetic resin sheet is plastic deformed or the temperature thereof exceeds a glass transition temperature so that the conductive bumps are pierced into the second synthetic resin sheet. In other words, the conductive bumps are pierced vertically into the second synthetic resin sheet so as to form through-type conducive lead portions exposed to the first (supporting substrate) and second synthetic resin sheets. The through-type conductive lead portions are used to electrically connect electric devices and circuit and to connect wiring pattern layers. The conductive bumps can be precisely and densely formed and disposed by printing method or plating method. The conductive bumps can be pushed and pierced into the second synthetic resin sheet. Moreover, the conductive bumps can be properly electrically connected to an opposed conductive layer. Thus, the circuit component provides high reliability and contributes to high yield and fabrication efficiency.