A first circuit element and a second element are mounted with their electrode forming surfaces facing a wiring layer. A first bump electrode formed integrally with the wiring layer on one face substantially penetrates a first insulating resin layer. A gold plating layer covering an element electrode of the first circuit element and a gold plating layer disposed on top of the first bump electrode are bonded together by Au—Au bonding. A second bump electrode formed integrally with the wiring layer on one face substantially penetrates the first and the second insulating resin layer. A gold plating layer covering an element electrode of the second circuit element and a gold plating layer disposed on top of the second bump electrode are bonded together by Au—Au bonding.