A transmittance-variable film, a use thereof, and a smart window including the same are disclosed herein. In some embodiments, a transmittance-variable film includes a first electrode substrate, a first electrode insulating layer disposed on the first electrode substrate, an electrophoretic layer, a second electrode insulating layer, and a second electrode insulating layer disposed on the second electrode substrate, wherein the first electrode substrate, the electrophoretic layer, and the second electrode substrate are sequentially arranged, and wherein the first and second electrode insulating layers contain a fluorine-based resin. Upon repeated driving of the film between a transparent mode and a black mode, the transmittance-variable film can maintain a transmittance constant in the transparent mode and exhibit an excellent light shielding ratio in the black mode.