A touch sensing device includes a touch screen coupled with a display panel including data lines, gate lines crossing the data lines, and pixels arranged in a matrix form, and a touch sensing circuit which supplies a driving signal to lines of the touch screen and senses a touch input. The touch sensing circuit detects an optimum sensing time, in which changes in a voltage change of the gate lines are maintained within a previously determined allowable range, in a touch screen drive period in which data is not written to the pixels of the display panel. The touch sensing circuit supplies the driving signal to the lines of the touch screen only in the optimum sensing time of the touch screen drive period.