An optical touch screen apparatus in which an oxide semiconductor transistor is used as a light sensing device, and a method of driving the optical touch screen apparatus. The optical touch screen apparatus includes an array including a plurality of light sensing pixels for sensing incident light, a gate driver for providing each of the light sensing pixels with a gate voltage and a reset signal and a signal output unit for receiving a light sensing signal from each of the plurality of light sensing pixels to output a data signal. The gate driver includes a plurality of gate lines that provide a gate voltage to each of the light sensing pixels and at least one reset line that provides a reset signal to each of the light sensing pixels and is electrically connected to the plurality of light sensing pixels.
