A laser crystallization apparatus and a crystallization method with a high throughput are provided. Laser light having a predetermined light intensity distribution is irradiated to a semiconductor film to melt and crystallize, wherein a irradiation position is positioned very quickly and with a high positional accuracy, thereby forming the semiconductor film having a large crystal grain size. A laser crystallization apparatus according to one aspect of the present invention comprises a laser light source, a phase shifter modulating laser light to give a predetermined light intensity distribution, marks provided on the substrate, a substrate holding stage moving in a predetermined direction, mark measuring means measuring a time at which the mark passes a predetermined position, and signal generating means generating a trigger signal indicating the irradiation of the laser light based on the measured time.