To prevent the base of a support from rusting owing to the stagnated water in the base and obtain a fine sight, by forming the whole to make a truncated cone and also forming an insertion opening at the upper horizontal part.

The whole body is shaped to form a truncated cone and an insertion opening 9 of a support is formed at the upper horizontal part to constitute a cover 8. The insertion opening 9 is formed to have such a dimension that a clearance is not brought between the support and the opening. And hence, the structure prevents penetration of water flowing along the outside face of the support into the cover 8. In this way, it prevents the base of the support from rusting owing to the stagnated water and provides an excellent fine sight by covering the mortar or sand exposed at the peripheral part of the support base with the cover body.