Disclosed is a method for manufacturing an electronic component device, including: preparing a sealing structure including a sealing layer having two opposing main surfaces, an electronic component, and a connection portion, the connection portion being exposed on a circuit surface that is one main surface of the sealing layer; preparing a rewiring structure including a rewiring portion having two opposing main surfaces, and a plurality of bumps; and bonding the sealing structure and the rewiring structure in a direction that the circuit surface and the plurality of bumps face each other, with an insulating adhesive layer intervening, and thereby connecting the sealing structure and the rewiring structure.