An image sensor is provided in the present invention, including a plurality of optical elements, wherein each optical element includes a semiconductor substrate, a dielectric layer and a color filter set. The semiconductor substrate includes a plurality of photosensitive units. The dielectric layer is disposed above the semiconductor substrate and includes a plurality of notches. The color filter set is disposed above the dielectric layer and includes a plurality of filter units and a plurality of convex substances corresponding to the filter units, and the convex substances and the notches are engaged with each other, wherein the convex substances and the notches change in accordance with the distance to the center of the image sensor.