A wiring board according to the present disclosure includes a core board including an upper surface, a lower surface, a through-hole penetrating from the upper surface to the lower surface, and a plurality of glass fibers located inside, and a through-hole conductor located in the through-hole. The through-hole conductor includes a first portion located on an inner wall of the through-hole, and second portions connected to the first portion and located inside the glass fibers. The second portions include portions in a first direction and a second direction intersecting the first direction in a planar direction of the core board, the portions having a shorter length in the planar direction from the inner wall of the through-hole than portions, of the second portions, in directions other than the first direction and the second direction.