Provided are an image sensor and a method of forming the image sensor. The image sensor has a base multi-layered reflection layer interposed between a photodiode and an interlayer insulating layer. The photodiode has a first surface adjacent to the interlayer insulating layer and a second surface opposite the first surface. Here, external light is incident on the second surface of the photodiode. Also, the image sensor includes a sidewall multi-layered reflection layer that encloses the photodiode.