Cap

A cap comprising:

• an inner cap which is installed in a mouth portion of a container body that accommodates contents;
• and
• an outer cap which is installed in the inner cap in a state in which relative movement thereof is restricted,
• wherein the inner cap is formed in a topped cylindrical shape in which it has an inner peripheral wall and an inner top wall,
• the outer cap is formed in a topped cylindrical shape in which it has an outer peripheral wall and an outer top wall,
• the outer peripheral wall includes
• an inner cylinder which is externally fitted onto the inner peripheral wall, and
• an outer cylinder which surrounds the inner cylinder from an outside in a radial direction,
• a plurality of elastic projection pieces which protrude downward and are formed to be elastically deformable in the radial direction, are provided at intervals in a circumferential direction at a lower end opening edge of the inner cylinder,
• lower ends of the plurality of elastic projection pieces are positioned above a lower end opening edge of the outer cylinder and below a lower end opening edge of the inner peripheral wall, and
• the plurality of elastic projection pieces include
• first elastic projection pieces in which support protrusions protruding inward in the radial direction and configured to support the lower end opening edge of the inner peripheral wall are formed in lower ends.