A valve mechanism adapted for a mouth portion of a tube-type fluid container includes: a valve seat portion having an opening through which a fluid passes; a disc-shaped valve portion; and an annular fixing portion for affixing the valve portion to the valve seat portion. The valve portion includes: an annular supporting portion, a closing portion for closing the opening, and multiple connecting portions connecting the closing portion to the annular supporting portion to urge the closing portion toward the opening. The annular supporting portion, the closing portion, and the multiple connecting portions are integrally formed.