Disclosed herein is a laser apparatus including: a laser oscillator configured to generate a laser beam; a plurality of mirror mount assemblies each arranged in one of predetermined reference transmission steps, each of the mirror mount assemblies including: a mount-side reflective mirror configured to reflect and transmit the laser beam; and an aligner configured to change alignment of the mount-side reflective mirror to adjust a machining optical path through which the laser beam transmitted by the mount-side reflective mirror travels; a laser nozzle assembly including a laser nozzle configured to radiate the laser beam transmitted from the mirror mount assembly located in the last step of the reference transmission steps onto an object to be processed; a database configured to store big data constructed to include optical path adjustment data indicating a pattern of selective adjustment of the machining optical path by the mount-side reflective mirror linked with the aligner according to a driving method of the aligner; and a controller configured to correct, when distortion occurs in the machining optical path, the distortion of the machining optical path by selectively driving the aligner provided in each of at least one mirror mount assembly among the mirror mount assemblies based on the big data using a driving method according to a pattern of the distortion of the machining optical path.