In a panel (400), a protrusion (nipple) (420) is formed, which is flattened when a tab is secured to the panel (400) and functions as a rivet. The protrusion (420) is provided at a section of the panel (400) which is surrounded by a first score line (430) and which is located on a top part (433A) side relative to one end (431) or the other end (432) of the first score line (430). A second score line (450) connected to a curved part (433) of the first score line (430) is provided in the panel (400). Consequently, a decrease in the outflow performance of the drink is suppressed and a decrease in operability of the tab is suppressed, even if the tab or the opening is increased in size or the panel is reduced in size.