A treatment-liquid application device includes a treatment-liquid container, a liquid supply unit, a liquid chamber unit, a treatment-liquid carrier, a transport unit, a treatment-liquid applicator, and a partition. The partition is disposed in an area of the chamber unit defined by an imaginary entry plane, an imaginary exit plane, a carrying surface of the carrier, and a bottom face of the chamber unit. The entry plane includes an entry line at which the carrying surface enters treatment liquid in the chamber unit, and vertically extends from the entry line. The exit plane includes an exit line at which the carrying surface exits from the liquid in the chamber unit, and vertically extends from the exit line. The partition extends in a longitudinal direction of the carrier and has an edge portion adjacent to the carrying surface.