To simultaneously construct a footing and a continuous footing part when constructing a building foundation and to prevent the camber of a member when placing concrete.

This member for constructing a building foundation is composed of a footing fitting 1 of long-sized thin plate shape provided with ruler parts 11 of a footing form B at both side parts and lifted at the intermediate part to form a placing part 12 for reinforcements E, and a continuous footing fitting 2 raised at both side parts with width corresponding to the erection width of a continuous footing form D and provided with a continuous footing form placing part 25 laid between both side parts of appropriate height.