Opening and closing member

An opening and closing member that opens and closes an opening by being attached to and detached from the opening of a container main body, the opening and closing member comprising:

• a top surface portion that covers the opening in a closed state where the opening is closed;
• a grip portion that extends to an outer edge of the top surface portion and grips an outer periphery of an opening end of the container main body in the closed state;
• and
• a depressurization path that penetrates into a tubular space formed in the grip portion and is attached to the grip portion, and depressurizes the space,
• wherein
• the top surface portion has an inner surface facing an inside of the container main body in the closed state where the opening is closed,
• the inner surface includes an annular inner surface annular region extending along an inner periphery of the opening end of the container main body, and
• the inner surface annular region includes:
• a protruding region portion provided with one or a plurality of protrusions protruding from the inner surface, and
• a flat region portion where the protrusion is not provided.