This invention relates to a NC laser apparatus comprising the combination of a numeric control apparatus and a laser machining apparatus. It includes a means for measuring the oscillation time of laser and a means (19) for measuring laser output power. When the oscillation time is within a predetermined time based on the life of optical components and the drop rate of the output power is below a predetermined value, an instruction for cleaning optical components is displayed on a display (18). When the oscillation time of the laser exceeds a predetermined time and the drop rate of the output power is below the predetermined value, an instruction to replace the optical components (5, 6) is displayed on the display (18). Accordingly, the maintenance becomes easy and the life of the optical components can be improved.