A sealing apparatus capable of increasing a grease resistance property, wherein the tip of a sealing lip is formed so that an inner side contact angle .alpha. is equal to an open-air side contact angle .beta. (.alpha.=.beta.), that is, formed in a triangular shape to prevent grease inside the apparatus from leaking so as to increase the grease resistance property, and since the extending direction of the sealing lip is set at a middle of an inner side and an open-air side, a trouble such as the inversion of the sealing lip due to the occurrence of an inner pressure does not occur.