A method of manufacturing an electronic device includes a step of housing an electronic component in a metal mold, then filling the metal mold with a molding material, wherein the metal mold includes a cavity having a rectangular planar shape and housing the electronic component, and a dummy cavity communicated with a side surface having the smallest gap with the electronic component out of four side surfaces included in the cavity, and in the step of filling the metal mold with the molding material, the molding material inflows into the cavity, and the molding material in the cavity inflows into the dummy cavity.