A moving mechanism relatively moves a machining head emitting a laser beam, with respect to a sheet metal along a surface of the sheet metal. A beam vibrating mechanism vibrates the laser beam for irradiation on the sheet metal in a predetermined vibration pattern, while the machining head is relatively moved by the moving mechanism. A vibration control section controls the beam vibrating mechanism to progressively reduce an amplitude of the vibration pattern from a first position to a corner portion when the machining head moves toward the corner portion and reaches the first position before the corner portion by a predetermined distance, and progressively increase the amplitude of the vibration pattern until the machining head reaches a second position ahead of the corner portion by the predetermined distance from the corner portion, at a time of producing a product having the corner portion.