A display device includes: a plurality of sensing data lines; a plurality of sensing units that output sensing signals through the plurality of sensing data lines; a signal selector that selects one sensing signal among the plurality of sensing signals; an automatic voltage adjusting unit that, when one sensing signal is selected by the signal selector, performs a controlling operation so as to allow a magnitude of the selected sensing signal to be in a predetermined range; and a voltage generator that adjusts the magnitude of the voltage applied to the sensing data lines based on a control signal output from the automatic voltage adjusting unit. According to the voltage adjusting operation, the sensing signal output through the sensing data line is always in an appropriate range. As a result, the touch determining operation on the sensing units can be accurately performed, so that it is possible to improve reliability of the sensing units.