PROBLEM TO BE SOLVED: To provide a gasket laminated with an inert resin film which has a reduced slide resistance value and high liquid encapsulation performance.SOLUTION: A gasket 10 for use in a medical syringe 30 is provided that comprises: a body 11 comprised of an elastic body； and an inert resin film 12 laminated on the surface of the body 11. The gasket 10 has a short columnar shape and has, on the outer circumferential surface 20 of the columnar shape, a plurality of annular ribs 13, 14 and 15 with sliding portions 16 to slide with the inner circumferential surface of the syringe. The plurality of annular ribs are aligned in an axial direction from the distal end of the gasket 10 toward its rear end, the linear length (a length in the axial direction) of the sliding portion of the annular rib 13 at the distal end occupying a ratio of 1-25%, with respect to the linear length of the outer circumferential surface 20 (a length in the axial direction of the outer circumferential surface) of the columnar shape.SELECTED DRAWING: Figure 1【課題】摺動抵抗値を下げ、かつ、液封止性の高い不活性樹脂フィルムで積層されたガスケットを提供する。【解決手段】弾性体で構成された本体１１と、この本体１１の表面に積層された不活性樹脂フィルム１２とを含む医療用注射器３０に用いられるガスケット１０であって、ガスケット１０は、短い円柱形状をなし、当該円柱形状の外側周面２０に、シリンジの内周面と摺接する摺接部１６を備えた環状リブ１３、１４、１５を複数有し、複数の環状リブは、ガスケット１０の先端から後端に向かって、軸方向に配列されており、先端の環状リブ１３の摺接部直線長さ（前記軸方向長さ）は、円柱形状の外側周面２０の直線長さ（外側周面の前記軸方向長さ）に対して、１～２５％の割合を占めている。【選択図】図１
