Abstract: A syringe includes an outer cylinder, a gasket having at least one part which slidably contacts the inner wall of the cylinder and being made of an elastomer material including a block copolymer having styrene units at both terminal ends, and means for sliding the gasket inside the cylinder. The slidably contacting part is compressed inside the cylinder at a compressiblity C (%) of a predetermined range selected according to a particular inner diameter of the cylinder. The product of the total contact area S (mm.sup.2) at the compressibility C (%) of the contacting part with the inner wall of the cylinder with the compressibility C (%) is about 350 to about 900.