To enable completion of a raising operation in a short time by providing a base plate having fitting holes provided outside, an appropriate number of spacers for raising which are set on the base plate and provided with through holes for a jack bolt and through holes for a connection bolt, and a manhole cover support.

Fitting holes 21 of a base plate 2 are fitted on anchor bolts 11 and the plate is fixed on a manhole side block 1 by fastening nuts 27. A required number of spacers 3-6 for raising are put on the plate 2, a manhole cover support 7 is put thereon, these members are connected by connection bolts 25 and nuts 26 and thereby a manhole cover support frame is fitted to the side block 1. In the case when a level difference occurs between the upper surface of the support 7 and that of an asphalt pavement 28, the connection bolts 25 are removed and the support 7 is raised by rotating a jack bolt 9 until the upper surface thereof comes to the same level as the road surface. Then, the support 1 is hoisted, a prepared spacer for raising is put in, the support 7 is lowered and fixed by the connection bolts 25 and the nuts 26 and thereby raising work is completed.