A laser processing system that can effectively blow out a material of a workpiece melted by a laser beam by effectively utilizing an assist gas emitted from a nozzle. The laser processing system comprises a nozzle including an emission opening configured to emit a jet of an assist gas along an optical axis of a laser beam, the nozzle being configured to forming a maximum point of velocity of the jet at a position away from the emission opening; a measuring instrument configured to measure the velocity of the jet; and a position acquisition section configured to acquire information representing a position of the maximum point based on output data of the measuring instrument.