A touch screen system according to an exemplary embodiment of the present invention includes: a touch screen panel including a plurality of driving electrodes coupled to a plurality of driving lines that extend in a first direction and a plurality of sensing electrodes coupled to a plurality of sensing lines that extend in a second direction crossing the first direction, the driving electrodes and the sensing electrodes being alternately arranged so as not to overlap with each other; and an active stylus separated from the touch screen panel, the active stylus configured to output an electric field in synchronization with driving signals that are applied to the driving lines coupled to the driving electrodes that are adjacent to the active stylus, wherein the driving electrodes and the sensing electrodes have different areas.