An image sensor includes a pixel array including a plurality of pixels configured to output pixel signals corresponding to a plurality of row lines; a row driver configured to output a plurality of control signals for controlling operations of the plurality of pixels; a plurality of analog-to-digital converters configured to perform analog-to-digital conversion on the pixel signals output from the plurality of pixels via a plurality of column lines so as to generate digital pixel signals, and to output the digital pixel signals; and a timing generator configured to generate a line control signal, the pixel array being configured to output the pixel signals corresponding to the plurality of row lines responsive to the line control signal. The pixel signals are output in a predetermined pixel unit in parallel from at least one row line among the plurality of row lines responsive to the row driver receiving the line control signal.