Laser device

An laser device comprising an optical path cover to be located on an optical path through which beam light travels, wherein

• the optical path cover includes a cylindrical portion through which the beam light is capable of passing, the cylindrical portion having a rectangular cylindrical shape, wherein
• on an inner wall of the cylindrical portion, the inner wall facing toward a side of an optical axis of the beam light, a plurality of protruding portions are formed, each of which has a convex shape in cross-section taken perpendicularly to the optical axis, while having an elongated shape along the optical axis, the protruding portions being arranged next to each other with the convex shape facing toward the side of the optical axis,
• the protruding portions are provided on each of inner walls facing each other in a certain direction in which a larger amount of unwanted light generated due to characteristics of the beam light diverges as compared to other directions, the certain direction being one direction perpendicular to the optical axis, the protruding portions protruding in the one direction, and
• each of inner walls facing each other in a direction perpendicular to the optical axis and perpendicular to the one direction has a flat surface.