To provide a medical rubber plug manufactured by a simple method and having high chemical resistance and airtightness.

The medical rubber plug is sealed by a cap that has a compressing annular protrusion 4 along an outer peripheral edge of a flange part of a rubber plug, and in which a leg part 1 coming into contact with a medicament and a lower surface of a flange 2 are laminated with a continuous inactive film 3. The medical rubber plug is molded by a single step, with a surface area from the outer edge part of the flange lower surface of the rubber plug is 50% or more, and surface roughness Ra in an area from an uppermost part of a leg part-side upper part to 1-5 mm below with the topmost defined as an origin is 0.1 μm or less.