An image sensor including a semiconductor substrate, a plurality of color filters, a plurality of first lenses and a second lens is provided. The semiconductor substrate includes a plurality of sensing pixels arranged in array, and each of the plurality of sensing pixels respectively includes a plurality of image sensing units and a plurality of phase detection units. The color filters at least cover the plurality of image sensing units. The first lenses are disposed on the plurality of color filters. Each of the plurality of first lenses respectively covers one of the plurality of image sensing units. The second lens is disposed on the plurality of color filters and the second lens covers the plurality of phase detection units.