A laser irradiation apparatus is provided with a laser oscillator, an articulated beam propagator in which a plurality of pipes are connected to each other in an articulated portion, and a course change means of a laser beam in the articulated portion. At least one pipe of the plurality of pipes includes a transfer lens for suppressing stagger of a laser beam in a traveling direction, in each pipe. The articulated portion produces degree of freedom in disposition of a laser oscillator, and the transfer lens enables suppression of change in beam profile.