An apparatus and method for preventing noise in a touch screen using a predetermined number of gates that substantially eliminates noise in advance and reduces cost includes an analog-to-digital converter (ADC) which converts received analog source data into digital source data, and sends the converted data. An input detection signal generator generates and sends an input detection signal containing information on a period from when the ADC receives analog source data to when the ADC finishes the conversion. A noise-preventing clock generator receives the input detection signal, generates a predetermined clock signal, and by referring to the information on the period contained in the received input detection signal, during the period from when analog source data is received to when the conversion is finished, disabling the generated clock signal and sending the clock signal. During the remaining period, the disabling is released and the clock signal is sent.