A laser annealing apparatus carries out an annealing treatment an amorphous silicon film on a TFT substrate. The apparatus includes: a mask having a plurality of apertures; a microlens substrate having a plurality of microlenses arranged on a surface thereof and configured to focus the plurality of laser beams Lb, that have passed through the respective apertures of the mask, onto the TFT substrate to apply a predetermined energy to the amorphous silicon film; a pair of guides each having a semi-cylindrical shape and disposed along both sides across the microlens substrate so that the axes of the guides are parallel to each other and that the tips of the guides protrude from the positions of tips of the microlenses toward the TFT substrate; and a film that is provided in a tensioned state between the pair of guides so as to be movable and that transmits a laser beam.