PURPOSE: To facilitate handling while almost quantitatively taking out content and to prevent the leakage of content by confirming a hermetically sealed state.

CONSTITUTION: An engaging part 23 is provided to a liftable plug body 3 and the engaging part 30 with the engaging part 23 is provided so as to hold the liftable plug body 3 to a falling state against the pushing-up force of a spring when the liftable plug body 3 falls and an elastic engaging piece 31 permitting the engaging part 23 to get over in an up-and-down direction is provided below the engaging part 23 and constituted in a freely elastically deformable manner so as to cover the engaging part 30 to make the engaging part 23 impposible to engage with the engaging part 30 when the engaging part 23 gets over from below to above.