A method for fabricating an electronic component embedded substrate including an electronic component that is embedded within a buildup layer is disclosed. The method includes a first buildup layer lamination step of laminating plural first buildup layers on a core substrate such that the total thickness of the first buildup layers corresponds to the thickness of the electronic component; a cavity formation step of forming a cavity for accommodating the electronic component at the laminated first buildup layers; an accommodating step of accommodating the electronic component within the cavity; and a second buildup layer lamination step of laminating a second buildup layer on the first buildup layers and the electronic component.