To provide a laser beam machining apparatus and its transportation and installation method by which the laser beam machining apparatus can be transported with a laser oscillator and an optical system assembled in the apparatus and by which installation of the apparatus at a customer's site can be performed in a short period of time.

The laser beam machining apparatus includes a holding means of a workpiece, an irradiation means of laser, and a base on which the holding means and the irradiation means are mounted. The irradiation means is constituted of a laser oscillator, a condenser, an optical system for guiding the laser oscillated by the laser oscillator to the condenser, and a frame on which the laser oscillator, the condenser and the optical system are arranged. The apparatus is equipped with a vibration-proof member arranged between the base and the frame, and a fixing means for fixing the frame to the base. When the laser beam machining apparatus is transported, the fixing means is released and the vibration-proof member is arranged between the frame and the base. When the laser beam machining apparatus is installed, the frame and the base are at least partly brought into tight contact with each other and fixed by the fixing means.