A laser processing method which can efficiently perform laser processing while minimizing the deviation of the converging point of a laser beam is provided.This laser processing method comprises a displacement acquiring step (S07 to S11) of irradiating an object to be processed with a rangefinding laser beam for measuring a displacement of a main surface of the object while converging the laser beam with a lens and acquiring the displacement of the main surface along a line to cut while detecting reflected light reflected by the main surface in response to the irradiation; and moves the processing objective lens and the object relative to each other along the main surface, while adjusting the gap between the processing objective lens and the surface according to the displacement acquired by the displacement acquiring step, thereby forming the modified region along the line to cut.