Provided is an image sensor including a semiconductor substrate including a first surface and a second surface and a plurality of pixel regions spaced apart, the plurality of pixel regions including a first region including a plurality of image pixels configured to generate image data and a second region including a plurality of phase difference detection pixels configured to perform autofocusing, a first grid pattern including a plurality of groove portions disposed on the second surface, a plurality of first microlenses selectively disposed on bottom surfaces of the plurality of groove portions corresponding to at least one of the first region and the second region, a plurality of color filters filling the plurality of groove portions, respectively, a second grid pattern superimposed on the first grid pattern, and a plurality of second microlenses separated by the second grid pattern and disposed on the plurality of color filters, respectively.