Provided is a focusing apparatus for an optical device, the focusing apparatus including a lead screw rotatably installed in the optical device, a carriage screw-coupled to the lead screw to move in a longitudinal direction of the lead screw in response to rotation of the lead screw, a lens barrel receiving at least one lenses and moving along the longitudinal direction of the lead screw, and a bridge extending from an outer circumferential surface of the lens barrel to enclose the carriage, in which the bridge moves the lens barrel in response to movement of the carriage.