Abstract: Provided is an application device for applying and spreading an application liquid to and on a predetermined application area of a target surface, which is capable of smearing the application liquid on the application area. The application device (D) includes a brush unit (4) having a brush bristle bundle (41a), and performs a step of causing, while moving a nozzle orifice (32a) of a dispenser (3) along at least a portion of the surface of a rivet (S1) and an area of a wall (Sp) surrounding the base of the rivet (S1), a sealing liquid to be ejected from the nozzle orifice (32a) and to adhere to the portion, and thereafter, a step of spreading the adhering sealing liquid by causing the brush bristle bundle (41a) to slide on the surface of the rivet (S1) and the area of wall (Sp) surrounding the base of the rivet (S1).