A CMOS image sensor includes a photo sensing device for generating photo charges, a floating diffusion region for storing the photo charges generated by the photo sensing device therein, a transfer transistor connected between the photo sensing device and the floating diffusion region for transferring the photo charges generated by the photo sensing device to the floating diffusion region, a reset transistor connected between a supply voltage terminal and the floating diffusion region for discharging the charges stored in the floating diffusion region to reset the floating diffusion region, a drive transistor for acting as a source follower buffer amplifier in response to an output signal from the photo sensing device, a switching transistor connected to the drive transistor for performing an addressing operation, and a charge control device connected between the photo sensing device and the transfer transistor for controlling the amount of charges stored in the photo sensing device.