A touch controller, a touch screen device, and an operating method of the touch controller are provided. A touch controller, performing a touch sensing operation of sensing a touch of a touch panel in a touch sensing period, includes a first clock generator configured to generate a low frequency clock signal for calculating the touch sensing period, a second clock generator configured to generate a high frequency clock signal for performing the touch sensing operation, and a first calibration circuit configured to calibrate a frequency of the low frequency clock signal by using the high frequency clock signal.