The invention relates to a method for machining a workpiece by means of a laser beam, in particular a part of a motor vehicle, wherein a laser beam is applied to the workpiece by means of a scanner, material of the workpiece is ablated, the radiation produced by the plasma during the process in the work area and/or reflected laser radiation is detected, and a signal is generated depending on the detected plasma and/or laser radiation. In addition the invention also relates to an apparatus for the laser beam machining of a workpiece, in particular for carrying out a method according to the invention. A greater process reliability can be ensured in laser beam machining in that the position of the laser beam in relation to the workpiece and/or the ablation depth is regulated and/or controlled depending on the signal.