Semiconductor-mounted device comprises wired board, first semiconductor chip mounted on first side of wired board, second semiconductor chip mounted on second side of wired board and sealing resin sealing, with a same height, a region disposed at and around first semiconductor chip and opposite, across wired board, to at least an area of projecting electrodes of second semiconductor chip; and a producing method thereof. Semiconductor-mounted device also comprises wired board, first semiconductor chip mounted on first side of wired board, second semiconductor chip mounted on second side of wired board and resin sheet covering, at substantially a same height as first semiconductor chip, a region disposed around first semiconductor chip and opposite, across wired board, to at least an area of projecting electrodes of second semiconductor chip, back surface of first semiconductor chip being exposed; and a producing method thereof.