A laser irradiation method includes a first scanning wherein a laser beam is scanned in a first region having a width in the X direction and a length in the Y direction by moving a laser irradiation area on the surface of the substrate along the Y direction using a spot laser beam, and a second scanning wherein laser beam is scanned in a second region having a width in the X direction and a length in the Y direction by moving a laser irradiation area on the surface of the substrate along the Y direction using the spot laser beam. A center of the second region is spaced apart from a center of the first region in the X direction.