PROBLEM TO BE SOLVED: To provide a method of positioning fixation of feed nozzles in a reactor used in FCC apparatuses which allows simple joining and fixation of feed nozzles.SOLUTION: In a method of positioning fixation of feed nozzles in a reactor 10 used in FCC apparatuses, a positioning restriction jig 22 is inserted into an upper opening of the reactor to mount a restriction member 23 on the outer peripheral edge 11a of the upper opening, and the center of a positioning member 25 is fitted to the central axis line of the reactor. The restriction member 23 is fixed to the outer peripheral edge part of the reactor, and a plurality of feed nozzles attached to an injector jig 20 are each inserted into the inside from hole parts bored preliminarily in the outer wall of the reactor so as to position the tip parts 20c of the injector jig 20 in the positioning member 25. The base end parts of the feed nozzles 12 extending out of the reactor are fixed to the restriction member 23, and the outer peripheries of th
