OPTICAL FILM, CIRCULARLY POLARIZING PLATE, AND ORGANIC ELECTROLUMINESCENT DISPLAY DEVICE

An optical film includes a cellulose derivative, the film having an in-plane retardation Ro550 within 120 to 160 nm measured at 550 nm wavelength, and a ratio Ro450/Ro550 of in-plane retardations Ro450 and Ro550 within 0.65 to 0.99, respectively, measured at 450 and 550 nm wavelengths, under a 23° C. atmosphere with a relative humidity of 55%, wherein, substituents of glucose skeletons of the cellulose derivative satisfy: part of the substituents have multiple bonds, and the average degree of substitution of the substituents having multiple bonds is within 0.1 to 3.0 per glucose skeleton unit; the maximum absorption wavelength of the substituents having multiple bonds is within 220 to 400 nm; and at least part of the substituents in the glucose skeletons form ether bonds with the glucose skeletons, and the average degree of substitution of the substituents having ether bonds is within 1.0 to 3.0 per glucose skeleton unit.