The invention discloses an anchor pre-tensioner for a safety seat belt of a vehicle. The anchor pre-tensioner for seat belt of vehicle improves phenomenon in which a webbing of seat belt is caught in belly of passengers during collision by the vehicle. The anchor pre-tensioner may include: first second wires connected to a lower end of the webbing respectively; a driving cylinder having a piston coupled to ends of the first and second wires; a gas generator supplying a gas pressure for the forward movement of the piston; a first roller supporting the first wire to move in the direction oblique against the bottom of the vehicle during the forward movement of the piston; and a second roller supporting the second wire to move downward when the piston moves forward; wherein the forward movement of the piston pulls the webbing of the seat belt in the direction where the first wire moves and at the same time in the direction perpendicular thereto.