A laser annealing method includes selecting a reference intensity from a plurality of intensities of a plurality of peaks; where the reference intensity is used to determine a pulse shape of laser irradiation during laser annealing, setting the pulse shape by setting an intensity ratio of a first peak having a smallest peak occurrence time among the plurality of peaks to less than about 100 percent relative to the reference intensity, and irradiating a laser beam having the pulse shape to a stage.