Laser processing device

This laser processing device includes: a stage 2 enabled to hover-convey a substrate 3 by ejecting a gas through a surface; a laser oscillator that projects a laser beam 20a on the substrate 3; and a gas ejection port for ejecting inert gas, arranged in a position that overlaps the focal position of the laser beam 20a in plan view. The surface of the stage 2 is constituted by upper structures 5a, 5b, the upper structures 5a, 5b being arranged so as to be separated from each other and opposing each other. The gap between the upper structures 5a, 5b, and the focal point of the laser beam 20a overlap in plan view. A filler element 8 is arranged between the upper structures 5a, 5b, plugging the gap between the upper structures 5a, 5b.