A wiring board includes an insulating substrate, a first conductor layer laminated on a first side of the insulating substrate, a second conductor layer laminated on a second side of the insulating substrate, first plating posts fitted in through holes in the insulating substrate respectively such that the first plating posts are projecting from the first conductor layer, and plating connecting parts connecting the second conductor layer and the first plating posts and having electronic component connecting portions such that the electronic component connecting portions form an electronic component mounting part positioned to mount an electronic component and are positioned on the through holes, respectively.