To form a leg part for keeping the space between a reinforcement holding tool and a form in a prescribed length by use of a material never rusting and having good bond strength with concrete in a form internal reinforcement support tool, prevent the damage of the leg part by a load while minimizing the area exposed to a concrete structure surface, and enhance the stability.

As the leg for keeping the space between a reinforcement holding tool 5 and the form in a prescribed length, a mortar cone 4 is used. A protruding part 3 having a prescribed width is circularly and integrally protruded down from the bottom 2 of its mortar cone body 1.