An optical apparatus includes a support stand, an optical module, a reflective module, at least a first adjusting unit and at least a second adjusting unit. The support stand has a base and a back frame. The back frame is connected with the base and formed an inclination angle with the base. The optical module is disposed on the base. The reflective module is disposed on the back frame. The first adjusting unit is connected with the back frame and the base. The first adjusting unit moves the back frame so as to adjust the inclination angle. The second adjusting unit is disposed at the back frame and contacts against the reflective module. The second adjusting unit moves the reflective module so as to adjust a swinging angle of the reflective module.