A method for machining an optical fiber comprises the steps of: connecting a rear end 1b of an optical fiber 1 to a laser oscillator 2 and exposing a clad 12 of a front-end 1a thereof; preparing processing agents 4-6 containing metal powder that can absorb a laser beam emitted from the laser oscillator 2; and soaking the front-end 1a of the optical fiber 1 into or bringing it into contact with the processing agent and, in this condition, emitting the laser beam from the laser oscillator 2 to irradiate the processing agent with it.