PURPOSE: To make an obstacle hard to be caught at the time of anchor casting and even if caught, make connection come off easily by providing a movable claw at a thick plate, fitting a connection stick and a guide stick to a shank provided with a guard portion, and connecting each to the thick plate and the thick plate or the movable claw.

CONSTITUTION: A movable claw 4 is provided at a thickness plate 1, and a connection stick 6 and a guide stick 7 are fitted to a shank 5 provided with a guard portion 11, and each is connected to the thick plate 1 and the thick plate 1 or the movable claw 4. A shape containing a crown 2 is made to be a fan shape of about 30° when viewed from the side surface, and the guide groove of the guide stick 7 of the penetration guide hole 9 of the guide stick 7 that is of a circular arc shape where the movable claw 4 moves, is provided, and the guard portion 11 is provided at the shank 5. When this anchor falls into an 'anchor away' state at the time of anchor casting, the thick plate 1 becomes perpendicular to the shank 5 and the connection stick 6, and the movable claw 4 becomes perpendicular in linkage with the shank 5 with its fitting position that is in the vicinity of the tip of the thick plate 1 as a fulcrum.