An object detection apparatus includes an incident optical system, which includes light source units and a combining unit combining light beams emitted from the light source units; a deflection unit including rotating reflection parts that deflect the light beams to scan and be irradiated on a predetermined range of an object; an imaging unit forming an image based on the light from the predetermined range of the object; and an optical detection unit detecting the object based on the light received via the imaging unit. Further the combining unit combines the light beams such that each of the combined light beams passes a single light path when projected onto a predetermined plane, and each of the light paths exists outside a region of the deflection unit when projected onto the first plane.