PURPOSE: To obtain an anchor difficult to slip off by a method wherein a notch section is formed to the leg section of the anchor having a notch in the axial direction, expansion at the time of driving is facilitated while an expansion plate is housed into the anchor and the leg section is reinforced.

CONSTITUTION: When notches 3b are formed to the leg section 3 of an anchor 1 having notches 3a in the axial direction and an accessory M is installed to light-weight concrete (ALC), etc., the leg section 3 is expanded easily. An expansion plate 4 consisting of a copper plate is housed into the leg section 3, and the leg section 3 is reinforced at the time of expansion while resistance force against drawing is increased. Accordingly, the anchor having strong drawing resistance force can be acquired.