In an optical path adjusting system, an x-axis wedge prism and a y-axis wedge prism are disposed in opposition to each other on the incident optical path side of a condenser lens to which a laser beam is incident so that the x-axis wedge prism and the y-axis wedge prism are displaceable in the directions of x and y axes of a surface of a work respectivley. A position of irradiation of the laser beam on the condenser lens is detected by a detector and the detected position of irradiation is inputted to a controller. The controller supplies a driver with an error correction signal representing an error of the position of irradiation relative to a reference position. The x-axis wedge prism and the y-axis wedge prism are dispalced by the driver so that the laser beam is corrected to be parallel to an optical axis of the condenser lens.
