To provide an inverse V shaped anchorage device capable of solving such a fact that a temporary roof is assembled by making use of a pipe or the like used for a scaffolding at a workshop, a vinyl sheet or the like is cov ered on the roof to take measures to prevent a leak in the roof and that the vinyl sheet or the like is torn by a projected pipe since the pipe or the like is projected in a V-shape by the conventional clamp anchorage device in part of the ridge.

Unless the pipe is projected in a V-shape in the part of the ridge, the vinyl sheet or the like used for the roof is not torn out. Accordingly, the inverse V shaped anchorage device is fixed to the ridge pipe to provide such a temporary vinyl sheet or the like that there is no leak in the roof even if it is torn.