An electronic component built-in wiring board includes a substrate having a cavity, an electronic component accommodated in the cavity of the substrate and having pads on a surface of the component, a coating insulating layer formed on the substrate such that the insulating layer is covering the component and has via holes, via conductors formed in the via holes such that the via conductors are penetrating through the insulating layer, and a resin coating formed between the component and the insulating layer and having through holes such that the through holes are partially exposing the pads in the via holes and that the coating has adhesion to the component that is stronger than adhesion of the insulating layer to the component. The via conductors are formed in the via holes and the through holes such that the via conductors are connected to the pads on the surface of the component.