Optical touch screen apparatuses with remote sensing and touch sensing by using a light sensor transistor including an oxide semiconductor transistor. The optical touch screen apparatus includes a pixel array of a plurality of sensing pixels arranged in a plurality of rows and a plurality of columns. Each of the sensing pixels includes a light sensing pixel for sensing light that is irradiated by an external light source and a touch sensing pixel for sensing display light that is reflected by a screen touch. The light sensing pixel includes a first light sensor transistor and a first switch transistor connected each other in series, and the touch sensing pixel includes a second light sensor transistor and a second switch transistor connected each other in series.