Abstract: In a mounting structure of a resin member, a collar has an outside diameter smaller than the diameter of a collar insertion hole of a resin-made fixation portion, and the collar defines a collar hole therein. A washer member defines a washer hole therein. The washer member has an outside diameter greater than the diameter of the collar insertion hole and an inside diameter smaller than the outside diameter of the collar. A holding portion throughhole of a metal-made holding portion, the collar hole, and the washer hole form a bolt insertion hole through which a bolt shaft is inserted in a state in which the collar is inserted in the collar insertion hole, the metal-made holding portion is laid on or over one surface of the resin-made fixation portion, and the washer member is laid on or over the other surface of the resin-made fixation portion.