An antenna device and method for manufacturing an antenna device, which can be bent to be cohered to installed position, and in which magnetic sheets can be mounted easily is provided. A method for manufacturing an antenna device incorporated in an electronic apparatus and communicating with an external device via an electromagnetic field signal, including arranging magnetic sheets on mutually different surfaces of one side part and other side part of an antenna coil, with respect to the antenna coil arranged by winding around a conducting wire such that parts of the conducting wire opposing in width direction via an opening will be close to each other, and divided into two parts; and pressing the antenna coil provided with the magnetic sheets in laminated direction.