A method of producing a thin IC card having a built-in battery includes forming a through-hole including an edge in a circuit board having obverse and reverse main surfaces, a circuit pattern being present on a first of the main surfaces of the circuit board; mounting a functional part on the first of the main surfaces of the circuit board; molding said circuit board and said functional part in a resin with a second main surface of said circuit exposed and forming a battery lodging section in the resin molding defined by the through-hole; and mounting a battery in said battery lodging section and electrically connecting the circuit pattern to the battery.
