There is provided a rubber stopper used to seal an opened portion of vials and syringes for keeping medical liquid and, in particular, to a rubber stopper in which stoppering properties can be improved without damaging sealing properties in the absence of silicone coating.A vial rubber stopper 1 comprises a disc-like top portion 3 and a cylindrical leg portion 2 of smaller diameter compared with that of the disc-like top portion, which is protruded from a bottom surface of the disc-like top portion 3 to shape into a flange 2A upward. Anunder-flange ring portion 3A connected to a flange bottom surface 2B is divided on an outer peripheral surface of the cylindrical leg portion 2, and the first ring-like raised portion 3B and the second ring-like raised portion 3C are formed downward of the under-flange ring portion 3A in the circumferential direction. An upper surface of the disc-like top portion 3 including a flange-upper surface, a maximum diametral portion of a flange-peripheral surface, a bottom surface of the disc-like top portion 3 located inside of the cylindrical leg portion 2 and a surface of the cylindrical leg portion 2 other than the under-flange ring portion 3A are laminated with a synthetic resin to leave the flange bottom surface and the surface of the under-flange ring portion 3A as a naked rubber stock.
