A hydraulic actuator comprising: an actuator main portion formed by a tube having a cylindrical shape that is expanded and contracted by pressure of fluid, and a sleeve formed as a structural body in which cords oriented in a predetermined direction are braided, the sleeve being configured to cover an outer periphery of the tube; and a sealing mechanism that seals an end portion of the actuator main portion in an axial direction of the actuator main portion, wherein: the sealing mechanism comprises: a sealing member inserted into the actuator main portion; a binding member arranged on an outer periphery of the actuator main portion into which the sealing member is inserted, the binding member being configured to bind the actuator main portion; and a locking member that locks the sleeve to the sealing member, and the sealing member comprises: a body portion inserted into the tube; a head portion continued to the body portion and arranged at an outer side in the axial direction with respect to the body portion; a flange portion arranged between the body portion and the head portion and protruded outward in a radial direction of the actuator main portion more than the body portion, the flange portion has a contact surface to be contacted with an end surface of the tube in the axial direction, and the sleeve is directly bound by the binding member and the flange portion, characterised in that the head portion has a contact surface to be contacted with an end surface of the binding member in the axial direction. an actuator main portion formed by a tube having a cylindrical shape that is expanded and contracted by pressure of fluid, and a sleeve formed as a structural body in which cords oriented in a predetermined direction are braided, the sleeve being configured to cover an outer periphery of the tube; and a sealing mechanism that seals an end portion of the actuator main portion in an axial direction of the actuator main portion, wherein: the sealing mechanism comprises: a sealing member inserted into the actuator main portion; a binding member arranged on an outer periphery of the actuator main portion into which the sealing member is inserted, the binding member being configured to bind the actuator main portion; and a locking member that locks the sleeve to the sealing member, and the sealing mechanism comprises: a sealing member inserted into the actuator main portion; a binding member arranged on an outer periphery of the actuator main portion into which the sealing member is inserted, the binding member being configured to bind the actuator main portion; and a locking member that locks the sleeve to the sealing member, and a sealing member inserted into the actuator main portion; a binding member arranged on an outer periphery of the actuator main portion into which the sealing member is inserted, the binding member being configured to bind the actuator main portion; and a locking member that locks the sleeve to the sealing member, and the sealing member comprises: a body portion inserted into the tube; a head portion continued to the body portion and arranged at an outer side in the axial direction with respect to the body portion; a flange portion arranged between the body portion and the head portion and protruded outward in a radial direction of the actuator main portion more than the body portion, a body portion inserted into the tube; a head portion continued to the body portion and arranged at an outer side in the axial direction with respect to the body portion; a flange portion arranged between the body portion and the head portion and protruded outward in a radial direction of the actuator main portion more than the body portion, the flange portion has a contact surface to be contacted with an end surface of the tube in the axial direction, and the sleeve is directly bound by the binding member and the flange portion, characterised in that the head portion has a contact surface to be contacted with an end surface of the binding member in the axial direction.