Provided are a comparison device capable of achieving a small area by using one small sampling capacitor for an input terminal and improving linearity by using a fixed reference voltage and a CMOS image sensor using the same. The comparison device may include a comparator configured to compare a pixel signal inputted through a positive input terminal with a ramp signal, a first sampling capacitor configured to be provided between an input terminal of the ramp signal and the positive input terminal of the comparator, a sampling switch configured to be provided between an output terminal of the comparator and a negative input terminal of the comparator, and a second sampling capacitor configured to be provided between a ground terminal and the negative input terminal of the comparator.