A machining head includes a machining head element having an inner-head channel for passing laser light and assist gas, the nozzle having an inner-nozzle channel connecting to the inner-head channel and a nozzle orifice, pins protruding radially inward from a curved inner surface of the nozzle, a pin-locking part formed on the outside of the machining head element, the pin-locking part having pin-fitting openings, a head alignment part formed on a nozzle-side end surface of the machining head element, a nozzle alignment part formed on the nozzle at a location where the nozzle is aligned with the machining head element, and an O-ring fitted between the head alignment part and the nozzle to create a clearance between the head alignment part and the nozzle alignment part for mutual alignment.