To adjust laying height of a concrete block easily and surely.

Insert holes 5 are penetratingly provided on the four corners of a plate-like concrete block 1. A shaft part 12 standingly povided on a base plate 11 is inserted to the lower end side of the insert hole 5, and the base plate 11 is fixed on the underside of the block by burying projecting parts 13 for anchor provided thereon in the block. A height adjusting bolt 10 is screwed in the upper end side of the insert hole 5. Accompanying screwing-in of the adjusting bolt 10, concrete surrounding the buried parts of the projecting parts 13 for anchor is broken, so as to separate the base plate 11 from the underside of the block. By further screwing the adjusting bolt 10 in, the base plate 11 is relatively moved downward, and hence the laying height of the concrete block is set into fixed height.