In the medical cap comprising a plug 10 made of thermoplastic elastomer and an outer frame 20 made of synthetic resin, the side surface part of the plug is contacted with an inner wall 211 of the side circuit part of the outer frame in a non-fused state and is held in a state with pressure applied from the leg part of the outer frame 22. As a result, the wetted surface of the plug is not flat shaped but has an inclination downward to the circle center. Protrusion 14 can also be provided on the wetted surface and in such a case, the bottom part of the protrusion part that is one part of the wetted surface has an inclination downward to the circle center.