An image sensor including: a pixel array including first and second pixel groups, each of the first and second pixel groups includes of pixels arranged in rows and columns; and a row driver configured to provide transmission control signals to the pixel array, the first pixel group includes a first auto-focus (AF) pixel including photodiodes arranged in a first direction, the pixels of the first pixel group output a pixel signal through a first column line, and the second pixel group includes a second AF pixel including photodiodes arranged in a second direction perpendicular to the first direction, the pixels of the second pixel group output a pixel signal through a second column line, and the first AF pixel of the first pixel group and the second AF pixel of the second pixel group receive same transmission control signals.