The present invention provides an image sensor. The image sensor comprises: a substrate, a plurality of optical elements, a first insulation layer, an anti-reflective coating (ARC) layer, a second insulation layer, and a color filter array. The optical elements are disposed in the substrate. The first insulation layer is disposed on the substrate and the optical elements. The ARC layer is disposed on the first insulation layer. The second insulation layer is disposed on the ARC layer. The color filter array is disposed on the second insulation layer, and the color filter array comprises a plurality of color filters corresponding to a plurality of different colors of light, respectively. The ARC layer comprises a plurality of sections directly below the color filters in a vertical direction, respectively, and the sections have different inherent reflection characteristics. The image sensor of the present invention can increase sensitivity and reduce crosstalk.