There are provided a laser processing unit easily detachable for replacement from the main body of a processing apparatus, excellent in maintainability, and capable of performing an efficient perforating operation and a processing apparatus having the laser processing unit. A casing detachable from the main body 1 of processing apparatus into which a work W is carried is composed integrally of a unit one half portion, a unit other half portion disposed in opposing relation to the unit one half portion with a work insertion space interposed therebetween, and a connecting portion for connecting the unit one half portion and the unit other half portion to each other. Optical means for guiding a laser beam emitted from a laser emission port into a processing area located above the unit other half portion and focusing the guided laser beam therein is provided in the unit one half portion. A beam receiving plate which transmits the laser beam is provided in the processing area.