A laser apparatus includes: a laser light source; an output member for receiving and transmitting a laser light flux generated by the laser light flux, and outputting a laser light flux; an optical aligning member for positioning the laser light flux generated by the laser light source to the output member; a drive for driving the optical aligning member; a drive controller; an output detector for outputting a detected output representing an intensity of a laser light flux outputted from the output member; and an output controller. The drive controller controls the drive to drive the optical aligning member and the output controller changes a power of the laser light flux generated by the light source, based on the detected output.