An electronic component device includes a first coreless wiring substrate, an electronic component mounted on the first coreless wiring substrate, a second coreless wiring substrate disposed above the first coreless wiring substrate and the electronic component such that the second coreless wiring substrate is spaced from the first coreless wiring substrate and the electronic component, a connection terminal that connects the first coreless wiring substrate and the second coreless wiring substrate, and a sealing resin filled between the first and second coreless wiring substrates. Each of the first and second coreless wiring substrates include an insulating layer, a wiring layer, and a reinforcing layer embedded in the insulating layer and provided in a region overlaying the electronic component.