The retardation film has a slow axis with an angle of 10 to 80° with respect to a longitudinal direction thereof and contains cellulose acylate having a degree of acyl substitution of 2.0 to 2.7 and a regulating agent. The retardation film has an in-plane retardation, measured at a wavelength of 550 nm, Ro550, of 115 to 260 nm. The retardation film has a ΔRo is 3 to 30 nm, where ΔRo is Ro550−Ro450, where Ro450 is the in-plane retardation of the film measured at a wavelength of 450 nm. The retardation film without the regulating agent has an in plane retardation, measured at a wavelength of 550 nm, Rc550, and ΔRc(Rc550−Rc450) equal to or greater than 0, where Rc450 is the in-plane retardation measured a wavelength of 450 nm.