An applicator insertable into a living body includes a nozzle having an elongated nozzle main body and a nozzle head on a front end side of the nozzle main body and through which a liquid together with a gas are expelled, with the nozzle main body including a flexible curved section. The applicator also includes an outer tube in which is positioned a portion of the nozzle main body so as to be movable along a longitudinal direction. An angle or a degree of curvature of the curved section is changed by inserting the curved section into the outer tube to thereby adjust a direction of the nozzle head relative to an axis of the nozzle main body. In addition, a longitudinally extending gap exists between the outer tube and the nozzle. The gap functions as a discharge path for discharging a gas within a body cavity.