An optical device includes a base that includes a main surface, a movable unit that includes an optical function unit, an elastic support unit that supports the movable unit so that the movable unit is movable along a predetermined direction perpendicular to the main surface, a fixed comb electrode that includes a plurality of fixed comb fingers, and a movable comb electrode that includes a plurality of movable comb fingers which are disposed alternately with the plurality of fixed comb fingers. At least one of the movable unit and the elastic support unit includes an electrode support portion that supports the movable comb electrode. The electrode support portion includes a rib portion that is formed so that the thickness of the electrode support portion in the predetermined direction is larger than the thickness of the movable comb fingers in the predetermined direction.