A method of manufacturing an electronic component mounting body is used for mounting an IC chip having a bumps as an external mounting terminal on a base material made of thermoplastic resin, comprising: a bump burying step of burying the bumps into the base material by heating and pressing the IC chip toward the base material to expose a portion of the bumps to a base material surface on the opposite side of the IC chip, and a step of forming a conductor conductively connected to the bump by arranging conductive material on the base material surface to which the portion of the bumps are exposed.