An optical sensor is provided, wherein the optical sensor includes an image sensing array, a collimator layer, and a light-shielding layer. The image sensor array includes a plurality of pixels. The collimator layer is disposed on the image sensor array and includes a plurality of openings corresponding to the pixels. The collimator layer includes a first surface facing the image sensor array and a second surface opposite to the first surface. The light-shielding layer is disposed on sidewalls of the openings.