An optical sensor is disclosed, including an irradiating system; a first photodetecting system including a first photodetector which is arranged on an optical path of a light which is specularly reflected from a subject; a second photodetecting system including an optical element which is arranged on an optical path of a light which is diffuse reflected from the subject within an incident face in the subject and which separates a linearly polarized component in a second polarizing direction which is orthogonal to a first polarizing direction and a second photodetector which receives a light separated by the optical element; and a restricting member which is arranged on an optical path of an incident light with respect to at least one of the first photodetector and the second photodetector and which restricts a light receiving range in the at least one photodetector.