A laser machining apparatus includes a main control unit executing NC program; a laser oscillator oscillating laser light according to instruction from the main control unit; a distance sensor measuring distance L between a nozzle and a workpiece; a sensor-data processing unit sampling a measured value of the distance sensor; and a copying control unit moving a machining head to maintain the distance constant based the measured value, wherein the sensor-data processing unit samples the measured value with an operation period shorter than that of the main control unit and, when a portion corresponding to the through hole in the workpiece comes off and the distance becomes larger than a predetermined value during the inner hole machining, causes oscillation of laser light to be stopped by outputting a stop signal to the laser oscillator.