PROBLEM TO BE SOLVED: To provide a lid of a vessel containing a substance such as a beverage, a medicine or the like for mixing two separately contained substances by a partial rotating operation, and the vessel. SOLUTION: The lid of the vessel has an additive containing member containing an additive, a cap member bonded to the additive containing member in the state of closing the lower end opening of the additive containing member, having the funnel-like additive flowing-out portion integrally formed in the inner side and screwed to a mouth neck portion in a state of circumscription, and an outlet opened and closed by elevating and lowering operations of the cap member. The lid further contains an opening and closing means tightly contacting the additive containing member of the cap member and fixed to the mouth neck portion of the vessel main body. The opening and closing means is a conical valve comprising a conical valve portion separating from or getting into contact with the additive flowing-out member in such a manner as to open and close the additive flowing-out portion of the cap member, many rim portions radially extending from the outer circumferential surface of the conical valve, and a ring connected to the outer edge portions of the rims so that it is constrained to the inner circumferential surface of the mouth neck portion of the vessel main body. COPYRIGHT: (C)2004,JPO&NCIPI