To provide a machining head having a combination lens which has a plurality of freely movable condenser lenses of different focal lengths inside and an adjustment mechanism for lens distances of the plurality of condenser lenses of different focal lengths and saves the handling time for replacing unnecessary lenses or a machining head, thus attains improvement in the mechanical working rate and production efficiency, and to provide a method for controlling the combination lens.

The machining head and the method are characterized by the fact that the plurality of condenser lenses of different focal lengths are provided in the machining head 1, the condenser lenses are independently movable, the adjustment mechanism for lens distances 2 is provided with which the relative positions of the plurality of condenser lenses of different focal lengths are varied and adjusted, and a control means which controls the adjustment mechanism for lens distances 2 is provided.