PURPOSE: To improve the reliability while lowering the noise by shortening the channel from power supply pad and ground pad of pellet to a capacitor by a method wherein a part of package is formed of the capacitor.

CONSTITUTION: A package substrate 2 comprising the first substrate 2a and the second substrate 2b is respectively fitted with electrode sheets 3a, 3b while electrode layers 4a, 4b conductive to the electrodes 3a, 3b are alternately laminated using ceramic layers 5 as intermediate layers. A cavity 8 is formed opposing to a mounted substrate 7 on the central part of substrate 2b to fix a pellet 6 on the surface of a power supply interconnection layer 9. The power supply interconnection layer 9 is conductive to the electrode sheet 3b serving both as an outer electrode of a capacitor element comprising the substrate 2a and a power supply electrode of the semiconductor device 1. In such a constitution, a ground interconnection layer 12 conductive to the electrode sheet 3a serves both as the outer electrode of capacitor element and the ground electrode of semiconductor device 1.