An optical deflector includes a mirror with a reflective layer on its front-side surface, a first support frame adapted to support the mirror, at least one torsion bar coupled between the first support frame and the mirror; and a reinforcement rib provided on a rear-side surface of the mirror. The torsion bar has a pair of protruded portions arranged symmetrically with respect to the torsion bar in the vicinity of a coupling portion between the torsion bar and the mirror. The reinforcement rib has a central portion and a pair of extension portions extended symmetrically from the central portion and coupled to the protruded portions, respectively, of the torsion bar.