PROBLEM TO BE SOLVED: To provide a method and a fixing structure capable of efficient fixing while keeping high waterproofness, and a fixing jig used in the method.SOLUTION: There is provided a roof plate material which comprises a lower seam 2 fitting on an upper seam of the roof plate material adjacently arranged for connecting the roof plate material to each other, and on which a recessed part 6 upwardly opening and extending from an edge to center of a roof is formed on the top part of the lower seam 2. Upon jointing a bottom wall part 6a of the recessed part 6 and a roof base material S disposed just below it with a stopper screw 8, a screw holding part 11 holding the stopper screw 8 is provided on the bottom wall part 6a of the recessed part 6 so that the lower seam 2 is pressed toward the roof base material S by the screw holding part 11 to have slight elastic deformation, and the stopper screw 8 is screwed based on the screw holding part 11 as a starting point while the deformed state is maintained. W
