This is to provide a laser irradiation apparatus which can drive a deflection optical system (33) with a high speed by a small and lightweight structure and can cope with heat generation of the optical system. The laser irradiation apparatus includes a condensing optical system (32) for condensing a laser beam (B) generated by a laser oscillator (10) at a predetermined focal point (FP), a deflection optical system (33) for deflecting the laser beam (B) generated from the condensing optical system (32) with a predetermined deflection angle, and a driving unit (100) for rotationally driving the deflection optical system (33) around a rotation axis provided substantially in parallel to an optical axis of the condensing optical system (32), wherein the driving unit (100) has an air motor (100) which convert an energy possessed by a gas supplied from a gas supplying source (60) to a rotational force.