To correct inexpensively or simply the focal point of a laser beam machine utilizing laser beams with a plurality of wavelengths.

The laser beam machine comprises a wavelength conversion element 20, a correction data storing means, a scanning means, a reference laser beam selecting means 3e, a focal point changing means, and a focal point change controlling means. The wavelength conversion element 20 produces harmonic laser beam having a harmonic wavelength against the wavelength of fundamental laser beam. The correction data storing means stores correction data in advance regarding changes in the focal point corresponding to each wavelength of the fundamental laser beam and harmonic laser beam. The scanning means is used to scan, on the face of a workpiece to be machined, the laser beam output from the wavelength conversion element 20. The reference laser beam selecting means 3e selects the reference laser beam for correcting the focal point on the face of the workpiece to be machined from the fundamental laser beam and the harmonic laser beam. The focal point changing means changes the focal point of the reference laser beam selected by the reference laser beam selecting means 3e. The focal point change controlling means reads out, from the correction data storing means, the correction data corresponding to the reference laser beam selected by the reference laser beam selecting means 3e and controls the focal point changing means on the basis of the read-out correction data.