An energy beam is irradiated to a workpiece through a beam transmission hole defined in a mask. At that time, a relative position between an energy beam source and the mask or the mask and the workpiece is changed, so that machining depth of the workpiece is varied depending on machining portions of the workpiece, which correspond to amounts of irradiation of the energy beam. With this method, a machined product having locally different depths very easily can be made and further the product can be machined to desired depths with high accuracy by a single machining operation in a short time.