A gasket usable with a washing machine capable of reinforcing the strength thereof while improving the vibration reducing performance of the gasket, a gasket connecting a tub to the front surface frame, wherein the gasket includes a body having a hollowness part configured to accommodate a portion of the door and a periphery part configured to surround the hollowness part, and a reinforcing rib formed by protruding at least one portion of the periphery part so as to reinforce a strength of the gasket, and wherein the reinforcing rib has a rear surface further concaved than an inner surface of the periphery part that is adjacent to the rear surface. The gasket further comprise a connection lip that contacts the closed door, such that the connection lip has a connection rib having a greater thickness in the lower portion of the lip than the upper portion of the lip.