Wiring substrate

A wiring substrate, comprising:

• an insulating layer having a plurality of through holes;
• a first conductor layer formed on a first surface of the insulating layer;
• a second conductor layer formed on a second surface of the insulating layer;
• and
• a plurality of interlayer conductors formed along wall surfaces surrounding the through holes respectively such that each of the interlayer conductors has a film-like shape forming a tubular structure with a hollow part and is connecting the first conductor layer and the second conductor layer,
• wherein the plurality of interlayer conductors includes a plurality of first interlayer conductors formed in a first region of the insulating layer and a plurality of second interlayer conductors formed in a second region of the insulating layer at a density higher than a density of the first interlayer conductors in the first region, and the plurality of interlayer conductors is formed such that a thickness of each of the first interlayer conductors in an end part of each of the first interlayer conductors is substantially same as or larger than a thickness of each of the second interlayer conductors in an end part of each of the second interlayer conductors and that a thickness of each of the first interlayer conductors in a center part of each of the first interlayer conductors is larger than a thickness of each of the second interlayer conductors in a center part of each of the second interlayer conductors.