There is provided a fiber laser processing machine, a fiber connection method and a fiber laser oscillator that are capable of improving the beam quality. A fiber laser processing machine comprises: a processing machine body provided with a laser processing head for emitting laser beams; a fiber laser oscillator including a fiber laser module for generating the laser beams and a feeding fiber cable for collectively taking out the laser beams generated by the fiber laser module; and a process fiber cable for transmitting the laser beams taken out by the feeding fiber cable of the fiber laser oscillator to the laser processing head of the processing machine body. The feeding fiber cable and the process fiber cable are joined by fusion, and the feeding fiber cable and the process fiber cable have an equal core diameter.