A substrate with a built-in electronic component includes multiple resin insulating layers including first, second, third and fourth insulating layers, multiple conductor layers including a first wiring layer including a first pad, a second wiring layer including a second pad, and a third wiring layer including third and fourth pads, multiple via conductors including a first via connecting the first and second pads through the second insulating layer, a second via connecting the second and third pads through the third and fourth insulating layers, and a third via connected to the fourth pad through the fourth insulating layer, and an electronic component positioned a cavity through the second and third insulating layers such that the third via is connecting terminal of the component and fourth pad. The second and third vias have filled plating filling opening portions through the third and fourth insulating layers and through the fourth insulating layer.