An object is to provide a vent plug having a structure in which an air-permeable membrane is unlikely to be damaged. More specifically, a vent plug is produced, which includes: a cylindrical member 1 having a through-hole 1a; a support 2 connected to the cylindrical member 1 so as to be across the through-hole 1a; and an air-permeable membrane 3 circumferentially attached to the cylindrical member 1, wherein the air-permeable membrane 3 is held on the support 2 and a convex portion 3a that follows the shape of the support 2 is formed on the air-permeable membrane 3.