A laser annealing apparatus includes a lens unit configured to transmit a laser beam to be irradiated onto an irradiation target; a lens unit housing accommodating the lens unit and having an opening configured to allow the laser beam to pass through the opening; a blocking plate configured to block at least a portion of the laser beam reflected by the irradiation target after being transmitted through the lens unit to the irradiation target; and a cooling unit between the blocking plate and the lens unit housing.