A through electrode extends through a silicon substrate from the upper surface to the lower surface of the substrate to accomplish electrical conduction between the upper and lower surfaces of the substrate. The through electrode includes a plurality of slender through holes formed in a through electrode forming area of the silicon substrate. The slender through holes extend through the silicon substrate from the upper surface to the lower surface of the silicon substrate. The through electrode also includes a plurality of conductive bodies fitted in the slender through holes. The conductive bodies are electrically connected with each other.