There are provided an electrode foil which has all the functions of a supporting base material, an electrode and a reflective layer and also has a superior thermal conductivity; and an organic device using the same. The electrode foil comprises a metal foil, wherein the electrode foil has at least one outermost surface which is an ultra-smooth surface having an arithmetic average roughness Ra of 10.0 nm or less as measured in accordance with JIS B 0601-2001.