An image sensor is disclosed, in which the image sensor changes the diameter of a lens from the center area of a chip to an edge thereof to obtain uniform sensitivity as a whole. The image sensor includes a plurality of light-receiving portions for converting a signal corresponding to the light of an object to an electrical signal, and a pixel array area having a plurality of micro lenses formed above the light receiving portions and respectively corresponding to the light-receiving portions to focus the light. In the image sensor, the respective micro lenses change their diameters from the center of the pixel array area to the edge thereof.