PURPOSE: To provide a height sensor device for a laser beam machine which is suitable for the cutting to the end part of a work and the welding of an angle shape, to improve the yield of the material, and to increase the kinds of the applicable welding shape.

CONSTITUTION: A sensor electrode 1 is held by a guard electrode 4, and provided with a first electrode part 1a and a second electrode part 1b which are split into two in the plane containing the axial direction of a beam hole, and the first and second electrode parts la, 1b are joined with each other through a joining insulating material 10. A selection switching means to select the function of the first and second electrode parts 1a, 1b according to the machining condition of a work 6 to be machined is provided.