A CMOS image sensor is provided to reduce the thermal noise and prevent deterioration of signals and maintain high sensitivity even at low luminance. The photo diode(100) produces photo-charge by the light. The transmission gate portion(200) transmits photo-charge to the first floating diffusion area(FDA1). The capacitance of the first floating diffusion region is increased. The transfer gate transmits the transmitted photo-charge to the second floating diffusion area(FDA2). The drive transistor(600) converts the photo-charge of the second floating diffusion area into the detection voltage. The reset transistor re-set the photo-charge of the second floating diffusion area. The selection transistor selects the output of the detection voltage.
