The electronic device includes a first interconnect layer and a second interconnect layer. The second interconnect layer is provided on the lower surface of the first interconnect layer. The first interconnect layer includes a via plug (first conductive plug). An end face of the via plug on the side of the second interconnect layer is smaller in area than the opposite end face. The via plug is exposed on the surface of the first interconnect layer facing the second interconnect layer. An insulating resin forming the first interconnect layer is higher in thermal decomposition temperature than an insulating resin forming the second interconnect layer.