The inner bottom (222b) of a female-like projection (22b) is provided with an elastic viscous material (4) continuous along the longitudinal direction so as to bulge into a space defined between hooks (221b, 221b) of the female-like projection (22b). When a female-like projection (21a) is fitted in the female-like projection (21b), the elastic viscous material (4) is pressed against the head (221a) of the male-like projection (22a) so as to be abutted against the head (221a) of the male-like projection (22a) while undergoing elastic deformation, and is in intimate contact with the surface of the front end side of the head (221a) by the adhesive force and elastic force, whereby the airtightness of the zipper-equipped bag can be secured.