A gasket (13) to be used for a syringe is provided, which includes a main body (14) made of an elastic material, and a film (15) provided on a surface of the main body (14). The gasket (13) has an annular groove (22) formed circumferentially in a surface portion of the film present in the circumferential surface portion thereof. The annular groove (22) has outer edge portions (24) provided along opposite edges (23) thereof as projecting from an unprocessed surface portion of the film. The annular groove (22) has a groove formation start point and a groove formation end point which are connected to each other in a groove connection region, and the outer edge portions (24) provided along the opposite edges of the annular groove have a maximum-to-minimum height difference of not greater than 5 µm in the groove connection region.
