A syringe piston used in fat transplantation is structured such that free oil is easily separated from suctioned fat by a syringe piston having a filter and naturally discharged through the rear side thereof. The syringe piston without a shaft, used in fat transplantation, disposed in a syringe-shaped cylindrical vessel, includes a piston body without the shaft, a packing coupled with an outer surface of the piston body to seal between the piston body and the syringe-shaped cylindrical vessel, a free oil discharging hole communicated with the front side and the rear side of the piston body, an opening and closing device for opening and closing the free oil discharging hole, and a filtering device disposed in a passage through which free oil is discharged to filter fat and pass the free oil.
