To provide an air plug which can be used for an airbag, can rapidly perform injection and exhalation of air, has no possibility of largely projecting in any case and does not become obstructive.

The air plug is equipped with an air feeding cylinder 21 used when air is fed into an air chamber 12, a plug body 22 to which this air feeding cylinder 21 is fitted, and a supporting part 23 for supporting this plug body 22. The supporting part 23 is equipped with a bottom part 23a for supporting the plug body 22, a surrounding part 23b standing up from this bottom part 23a and surrounding the whole air feeding cylinder 21, and a flange part 23c integrated with the upper edge of this surrounding part 23b and fitted with a flexible sheet 11.