An inspection apparatus for a laser oscillator includes a dimming plate that dims a laser beam immediately after the laser beam is emitted from the laser oscillator; an imaging unit that images, with a plurality of pixels, the laser beam dimmed by the dimming plate; a processing unit that processes an image captured by the imaging unit; and a display unit that displays the image processed by the processing unit. The processing unit has at least two thresholds of an inner ring and an outer ring used for partitioning the intensity of the laser beam.