The present invention relates to a method of manufacturing integrated circuit device package having a flexibility, the method comprising the steps of More specifically prepare the first flexible board (FCCL) equipped with a first conductive layer on the top surface, the top surface of the first flexible substrate a first conductive layer provided with the step of forming a pattern the first circuit and the mounting portion is removed in part on the specified circuit, comprising the steps of mounting the first integrated circuit element on a mounting portion of the first flexible substrate, wherein the method comprising mounting a second integrated circuit element on a first integrated circuit element mounted on the flexible substrate, the first of the first circuit pattern on the flexible substrate, a first integrated circuit element and the second integrated circuit device is built-in so forming a mold layer, comprising the steps of: the first corresponding to the terminal position of the integrated circuit element and a second integrated circuit element forming a plurality of through holes in said mold layer, said through-holes in the molding layer surface formed subjected to copper plating to form a second conductive layer, and wherein the through holes have respectively copper is filled via and forming (via), partially removing the second conductive layer corresponding to the via to form a terminal pattern the method comprising, by bonding a solder ball to the terminal pattern corresponding to the via, consists of steps for completing the device package directly with the flexible circuit, providing an integrated circuit device package that is bent at an angle, and integrated circuit elements and the base board by the electrical connection between the copper (Cu), and can lower the production cost, it can reduce the signal loss to a minimum, and the thickness of the package provide a composite integrated circuit device package manufacturing method which can be produced thinner than the conventional.