A printed wiring board comprises ground layers stacked via insulator(s); a first through hole; second through holes ; and signal wirings each extending from the first through hole through the clearance between predetermined ones of the ground layers, disposed between predetermined second through holes of the second through holes. Each of first clearances in the ground layers neighboring layer in which the signal wiring is disposed has an outline that a distance between the first through hole and outline of the first clearance is minimum of the signal wiring. Each of second clearances in the ground layers not adjacent to the signal wiring has an outline formed outside a circle connecting each center of second through holes centering the first signal through hole, such that outline of second clearance does not contact with the second through holes.