A sheet capacitor of the invention has a contact portion formed in a through-hole requiring electrical connection with an IC connection pin among the through-holes in which the IC connection pins are inserted, and a capacitor element connected to the contact portion. Another sheet capacitor of the invention includes an insulating board and a capacitor element mounted on the insulating board. The insulating board has a connection land with an IC at the upper side, and a connection land with a printed wiring board at the lower side. The capacitor element and connection lands at the upper and lower side of the insulating board are connected with each other electrically. In any one of these configurations, a capacitor element of large capacity and low ESL is connected closely to the IC, and the mounting area of the peripheral circuits of the IC can be increased.