An image sensor includes: a plurality of image pixels providing a reset signal and a data signal; a signal providing apparatus generating a ramp signal, and sequentially providing the reset signal, the data signal, and the ramp signal; and an analog-to-digital converting apparatus converting the data signal into a digital signal by using a first timing at which the amplitude of the ramp signal is changed based on the amplitude of the reset signal and a second timing at which the amplitude of the ramp signal is changed based on the amplitude of the data signal, wherein the reset signal used to generate the ramp signal and the data signal which has been converted into the data digital signal may be output from the same image pixel.