An image forming apparatus includes an image forming unit for forming an image on a medium; and an application device for applying a treatment liquid to the medium. The application device includes a conveying roller; an application roller for applying the liquid; a squeeze roller for reducing the thickness of the liquid on the application roller; and a tray for supplying the liquid to the squeeze roller. In the application operation, the application and squeeze rollers come in contact, and a valley formed by these rollers faces upward. In the standby condition, at least one of the application and squeeze rollers is moved to such a position that the valley faces laterally. The tray always covers the lower side of the application and squeeze rollers in regions near the longitudinal end portions of the application roller, which end portions do not come in contact with the conveying roller.