Disclosed are a CMOS image sensor and a method for manufacturing the same, capable of improving the characteristics of the image sensor by increasing junction capacitance of a floating diffusion area. The CMOS image sensor generally includes a photodiode and a plurality of transistors (e.g., transfer, reset, drive, and select transistors), a first conductive type semiconductor substrate, having an active area including a photodiode area, a floating diffusion area, and a voltage input/output area, a gate electrode of each transistor on the active area, a first conductive type first well area in the semiconductor substrate corresponding to the voltage input/output area, a first conductive type second well area in the semiconductor substrate corresponding to the floating diffusion area, and a second conductive type diffusion area in the semiconductor substrate at opposed sides of each gate electrode.