An object of the present invention is to provide an optical film exhibiting a preferable wavelength dispersion and capable of being formed comparatively thinly.The present invention is an optical film containing the repeating unit represented by the following general formula (II).In the formula (II), A, A′, B, and B′ each denote a substituent, a, a′, b, and b′ denote the number of substituents of the corresponding A, A′, B, and B′. A, A′, B and B′ each independently denote a halogen or an alkyl group having 1 to 4 carbon atoms. R1 and R2 denote a halogen, an alkyl group having 1 to 10 carbon atoms, and the like. X denotes —CO—, —SO2—, and the like.