A manhole cover support cooperable with a manhole frame for raising the elevation of a manhole cover utilizes a gapped support body positionable between the frame and the manhole cover and size-adjustment mechanisms for altering the size of the outer periphery of the support body. The support body includes one section disposed on one side of its gap and another section disposed on the opposite side of its gap, and the size-adjustment mechanisms include a threaded shank attached to the one section of the support body so as to extend across the gap provided therein. The size-adjustment mechanisms also include a U-shaped bracket attached to the another section of the support body so that the portion of the threaded shank which extends across the gap is accepted by the U of the U-shaped bracket and further includes a nut threaded upon the shank so as to be disposed between the attached end of the shank and the bracket. By rotating the nut about the shank so that the bracket is moved away from the attached end of the shank by the nut, the outer dimensions of the support body are increased. The inside surface of the U of the U-shaped bracket is shaped to accommodate a shifting of the shank relative thereto in a manner which reduces the exposure of the bracket and shank to undue strain from one another.