A lid for closing a mouth of a container, and is made of a material principally including a paper material, the lid comprising: a side wall for being fitted to the mouth of the container; and a top lid that is surrounded by the side wall, wherein the top lid includes: an inlet/outlet formation part that forms an inlet/outlet for an article stored in the container; and the inlet/outlet formation part is mounted with a sticker member, wherein the inlet/outlet formation part includes an inlet/outlet and a closing piece for closing the inlet/outlet, wherein the sticker member is joined to the closing piece, the sticker member includes one end that is mounted to the closing piece, and another end that opposes the one end, and the another end of the sticker member is mounted on a surface of the top lid in a peelable state, a first joint joined to the closing piece is formed at the one end of the sticker member, the closing piece has one end that is located away from a center of the top lid and is a free end, and another end that is located close to the center of the top lid and is a fixed end, and the closing piece is configured to be opened/closed by a hinge formed at the another end of the closing piece. a side wall for being fitted to the mouth of the container; and a top lid that is surrounded by the side wall, wherein the top lid includes: an inlet/outlet formation part that forms an inlet/outlet for an article stored in the container; and the inlet/outlet formation part is mounted with a sticker member, wherein the inlet/outlet formation part includes an inlet/outlet and a closing piece for closing the inlet/outlet, wherein the sticker member is joined to the closing piece, the sticker member includes one end that is mounted to the closing piece, and another end that opposes the one end, and the another end of the sticker member is mounted on a surface of the top lid in a peelable state, a first joint joined to the closing piece is formed at the one end of the sticker member, the closing piece has one end that is located away from a center of the top lid and is a free end, and another end that is located close to the center of the top lid and is a fixed end, and the closing piece is configured to be opened/closed by a hinge formed at the another end of the closing piece. an inlet/outlet formation part that forms an inlet/outlet for an article stored in the container; and the inlet/outlet formation part is mounted with a sticker member, wherein the inlet/outlet formation part includes an inlet/outlet and a closing piece for closing the inlet/outlet, wherein the sticker member is joined to the closing piece, the sticker member includes one end that is mounted to the closing piece, and another end that opposes the one end, and the another end of the sticker member is mounted on a surface of the top lid in a peelable state, a first joint joined to the closing piece is formed at the one end of the sticker member, the closing piece has one end that is located away from a center of the top lid and is a free end, and another end that is located close to the center of the top lid and is a fixed end, and the closing piece is configured to be opened/closed by a hinge formed at the another end of the closing piece.