LASER PROCESSING APPARATUS AND COUPLER

A laser processing apparatus includes: at least two first input optical fibers; an output optical fiber; a coupler configured to optically couple a first end of a bundle portion, in which the at least two first input optical fibers are bundled, to a second end of the output optical fiber; at least one first light source optically connected to one of the first input optical fibers to output laser light; and an optical head optically connected to the output optical fiber to output laser light and passing through the first input optical fiber and the output optical fiber. In a cross section intersecting an axial direction of the first end, a cladding of the first input optical fiber has an extending portion extending linearly in a direction intersecting the axial direction between cores of two first input optical fibers adjacent in a circumferential direction.