The embodiment relates to a complementary metal oxide semiconductor (CMOS) image sensor and more particularly, to a CMOS image sensor and a manufacturing method thereof capable of improving electron storing capacity in a floating diffusion area. The CMOS image sensor includes a first gate electrode on a semiconductor substrate; a photodiode in the semiconductor substrate on one side of the first gate electrode; a floating diffusion area in the semiconductor substrate on an opposite side of the first gate electrode; a capacitor including a lower capacitor electrode connected to the floating diffusion area, a dielectric layer on the lower capacitor electrode, and an upper capacitor electrode; a drive capacitor coupled to the lower capacitor electrode and having a second gate electrode connected to the floating diffusion area. The electron storing capacity of the floating diffusion node is increased, making it possible to improve the dynamic range of the image sensor.