To provide a structure for fixing a guard fence which enables a vehicle to smoothly pass through an opening of a medial strip particularly when the guard fence installed in the opening of the medial strip is removed.

Since a guard fence bolt member 7 is screwed into a fastening nut member 62, the guard fence bolt member 7 can be removed from a foundation 5 together with a double nut which is screwed into the upper end of the guard fence bolt member 7. Thus, since a top surface side of the foundation portion 5 can become almost flat in a state that the guard fence 3 is removed, the vehicle can smoothly pass through the opening.