A method for manufacturing an electronic component device in which an electronic component and a heat dissipating member are connected by a heat conducting member, the method comprising forming one of a plate shape metallic member and a recessed metallic member on the electronic component by a selected one of vapor deposition processing and plating processing, forming the other of the plate shape metallic member and the recessed metallic member on the heat dissipating member by a selected one of vapor deposition processing and plating processing, and filling a liquid metal in the recessed part of the recessed metallic member thereby to form the liquid metal, the plate shape metallic member and a part of the recessed metallic member into a solid solution.