To provide a guard fence support which can be arbitrarily set on a place of a gradient, and does not require a large-scale reinforcing structure even if it is for use in application that a large shock such as a collision of a vehicle may be imposed thereon.

A support body 20 is made rotatable by fitting arched convex portions 1 and arched convex portions 4 to each other, and can be arbitrarily set on a place of a gradient. By to the structure of the guard fence support, each flange 3 is inserted into a mounting groove 2 and bolted to the groove, and therefore even if a large shock is imposed, stress is dispersed to the mounting groove 2 and a fitting portion between the convex portion 1 and the concave portion 4, to thereby avoid the concentration of the stress near a bolt B. As a result even if the guard fence support is for use in the application that a collision etc. of a vehicle may occur, the large-scale reinforcing structure is not required.