Disclosed is a CMOS image sensor comprising a unit pixel which includes a photodetector (e.g., photodiode); an erasing transistor which, being connected to the photodetector, controls the exposure integration time of the photodetector by time division; a charge storage (e.g., floating diffusion region) in which the charge accumulated in the photodetector is transferred and stored; and a transfer transistor which, being connected between the photodetector and the charge storage, transfers the charge accumulated in the photodetector to the charge storage; wherein a first signal charge accumulated in the photodetector during the first exposure integration time is transferred to the charge storage and stored therein, and the second signal charge is accumulated in the photodetector during the second exposure integration time, thereby sequentially reading out signals in response to the first signal charge and the second signal charge at a time of sampling out the information on signal charge stored in the unit pixel.