A touch sensor including: a touch sensing area including driving electrodes and sensing electrodes; a driving signal generator which determines phases of driving signals based on a reference code and supplies the driving signals to the sensing electrodes, wherein the driving signals are sine waves; and a touch processor which receives sensing signals according to the driving signals from the sensing electrodes and determines a touch position based on the sensing signals and the reference code, wherein the driving signal generator controls the phases of the driving signals by updating the reference code at a predetermined time point.