PURPOSE: To increase the reliability of a multilayer printed wiring board by ensuring the nonconductive state between through holes for connecting conductor pattern formed in different layers, and an inner-layer power source layer or grounding layer.

CONSTITUTION: A multilayer printed wiring board is provided with an inner layer having power source surfaces 3a and 3b of a grounding surface 4. And circular clearances 6 for through holes are formed in the power source surface 3a and 3b or a grounding surface 4. When two clearances 6, or a clearance 6 and an isolating pattern 5 exist touching each other, the shape of the clearances 6 is corrected so that the exterior angle formed by the outline of a conductor layer existing between the clearances 6 adjoining, or between the clearance 6 and the isolating pattern 5 may be a right angle or more.