To exhibit ensured tamper evident characteristics in a cap that is capable of opening only part of the mouth of a container when its contents are used, and capable of achieving a level measuring spoonful of contents by the uses of a fixed section of the cap.

In the plastic cap 1 having a top plate and a skirt, the internal circumferential face of the lower end of the skirt 41 has an engaging projection that engages with an engaging projection 32 formed on the external circumferential face of the mouth of the container, and a straight thin wall is formed on the internal face of the top plate. The skirt 41 corresponding to both ends of the straight thin wall have breakable thin walls continuing from the straight thin wall and extending down. In addition, the straight thin wall and the breakable thin walls define an opening section in which a handle is formed on the external face of the skirt opposite to the straight thin wall, and the fixed section other than the opening section. The lower end of the skirt has, via a weak section, a tamper evident band 6 that has an inside diameter greater than the outside diameter of the lower end of the skirt.