A projection head lamp assembly for a vehicle may include a bulb irradiating light, a reflector supporting the bulb and reflecting the light irradiated from the bulb to the front, a shield unit including a shield shaft supported by the reflector and a shield integrated on the shield shaft, a drive cam inserted into one end of the shield shaft to be rotated according to a straight movement of a solenoid, and a lens connected to the front of the reflector. The projection head lamp assembly may further include a return spring provided on an outer circumference of the shield shaft, and weights inserted into both ends of the shield shaft for preventing free movement of the shield shaft when the shield shaft is rotated.