1. An angle detection apparatus that detects an inclination angle of a detection object, comprising: a light source that irradiates light onto a reflective surface for detection provided on said detection object; an optical path splitting element that splits an optical path of reflected light that has been reflected by said reflective surface for detection; and a plurality of optical detectors that each receive a luminous flux split by said optical path splitting element, and each independently detect an inclination angle of said reflective surface for detection.