A laser crystallization monitoring device includes a stage that supports a substrate, a laser beam generator that emits a laser beam to the substrate, a mirror that reflects the laser beam emitted from the laser beam generator and that rotates around a rotation axis, a first telecentric f-theta lens located on the laser beam path between the mirror and the substrate, a second telecentric f-theta lens through which the laser beam reflected from the substrate passes, and a monitor that inspects the laser beam passing through the second telecentric f-theta lens.