A laser apparatus may include a master oscillator, an optical unit provided in a beam path of a laser beam from the master oscillator, a beam adjusting unit provided upstream from the optical unit in a beam path of the laser beam and configured for adjusting at least one of a beam path and a wavefront of the laser beam, a first detection unit provided between the beam adjusting unit and the optical unit in a beam path of the laser beam and configured for detecting the laser beam, a second detection unit provided downstream from the optical unit in a beam path of the laser beam and configured for detecting the laser beam, and a controller configured for controlling the beam adjusting unit based on outputs from the first and second detection units.