The present invention is to provide a retardation film having excellent durability against temperature change or the like and a production method of the retardation film. Particularly, the present invention is to provide a retardation film which realizes both reverse wavelength dispersion and durability and a production method of the retardation film. This is achieved by a retardation film including: a component (A) which is specific cellulose acylate; and a component (B) which is cellulose acylate or cellulose ether having a molecular weight different from a molecular weight of the component (A) and whose residual degree of hydroxyl group is 0.30 or more.