An optical sensor includes a plurality of pixels disposed in a substrate and a light collimating layer. The light collimating layer is disposed on the substrate. The light collimating layer includes a light-shielding layer, a plurality of transparent pillars, and a plurality of first dummy transparent pillars. The light-shielding layer is disposed on the substrate. The plurality of transparent pillars pass through the light-shielding layer and are disposed correspondingly on the plurality of pixels. The plurality of first dummy transparent pillars that pass through the light-shielding layer are disposed on a first peripheral region of the light collimating layer, wherein the plurality of first dummy transparent pillars surround the plurality of transparent pillars from a top view.