A dummy pin and a waterproof connector , the waterproof connector including: a housing that has at least one terminal insertion port ; and a waterproof member that is elastically deformable, is disposed in the housing and has at least one seal hole corresponding to the at least one terminal insertion port and having a central axis (CI), the at least one seal hole having two or more lip portions that annularly project toward the central axis and are aligned in a direction of the central axis, the dummy pin comprising: a pin main body that is to be inserted into the at least one terminal insertion port and is formed by molding resin, wherein the pin main body has: a waterproof portion having a cylindrical seal surface that is configured for making tight contact with an inner surface of the at least one seal hole by elastically compressing a part of the two or more lip portions of the waterproof member; and a falling-off prevention portion having one or more concave portions that are partially recessed from the seal surface toward the central axis and being configured such that a remaining lip portion of the two or more lip portions of the waterproof member enters said one or more concave portions , and the seal surface forms a continuous surface over an entire circumferential direction of the waterproof portion , further comprising a head portion that is joined to one end of the pin main body in a length direction thereof and has a size larger than an inside diameter of the at least one terminal insertion port wherein the pin main body has a fitting portion to be fitted with the at least one terminal insertion port, the fitting portion being positioned closer to the one end of the pin main body in the length direction than the waterproof portion and having an outside diameter larger than that of the seal surface. further comprising at least one press-fitting rib on a surface of the fitting portion . a pin main body that is to be inserted into the at least one terminal insertion port and is formed by molding resin, wherein the pin main body has: a waterproof portion having a cylindrical seal surface that is configured for making tight contact with an inner surface of the at least one seal hole by elastically compressing a part of the two or more lip portions of the waterproof member; and a falling-off prevention portion having one or more concave portions that are partially recessed from the seal surface toward the central axis and being configured such that a remaining lip portion of the two or more lip portions of the waterproof member enters said one or more concave portions , and the seal surface forms a continuous surface over an entire circumferential direction of the waterproof portion , further comprising a head portion that is joined to one end of the pin main body in a length direction thereof and has a size larger than an inside diameter of the at least one terminal insertion port wherein the pin main body has a fitting portion to be fitted with the at least one terminal insertion port, the fitting portion being positioned closer to the one end of the pin main body in the length direction than the waterproof portion and having an outside diameter larger than that of the seal surface. further comprising at least one press-fitting rib on a surface of the fitting portion . <EOS>