A fixing structure (A) in which screw engagement members (4) are applied to mating thread portions (3a) formed in a fixed member (3) through mounting holes (5a) provided in a mounting member (5) and having a larger diameter than the outer diameter of the screw engagement members (4) to hold the mounting member (5) of the fixed member (3), said fixing structure (A) is characterized by the provision of engaging members (6) of elastic material which have a free size outer diameter nearly equal to or smaller than the bore diameter of the through mounting holes (5a) of the mounting member (5) for engaging said screw engagement members (4), so that the elastic engaging members (6) radially expand as the screw engagement members (4) move toward engagement with the fixed member (3) to engage themselves with the outer circumference or inner wall of said through mounting holes (5a) of the mounting member (5) for securely fixing said mounting member (5) to said fixed member (3).
