PURPOSE: To effectively prevent the malfunction of a circuit caused by cross talk, etc., and decrease the area of a chip, by shielding between adjacent wiring layers including signal lines with a conductive layer exclusively used for a neutral signal.

CONSTITUTION: A metal layer 20 is formed on the whole surface above first layer wirings 12W14 through a layer insulating film 15. The metal layer 20 is connected to wiring 14 for a GND line through the through hole of the layer insulating film 15. Third layer metal wiring 22 is formed on the metal layer 20 through a layer insulating film 21 and a passivation film 23 is formed on the wiring 22. Forming the metal layer 20 on the whole surface and making the layer insulating films 15 and 21 of for example 1.2μm or more thickness respectively can reduce the parasitic capacity enough to ignore.