A laser surgical apparatus for performing treatment by irradiating a part to be treated by a laser beam is disclosed. This apparatus includes a laser source which emits the treatment laser beam; a multi-articulated arm for delivering the treatment laser beam emitted from the laser source, the arm including a plurality of light delivery pipes, a joint part for jointing the light delivery pipes, the joint part being rotatable with respect to at least one of the pipes jointed by the joint part, a reflection mirror disposed in the joint part; and a surgical instrument is connected to an end of the arm and used for irradiating the treatment laser beam delivered therein through the arm to the treatment part.