An optical film including a transparent polymer film (b) and a birefringent layer (a) formed of a polymer and laminated above the transparent polymer film (b) is provided. The birefringent layer (a) and the transparent polymer film (b) satisfy the following formula (1), the birefringent layer (a) satisfies the following formulae (2) and (3), and the polymer forming the birefringent layer (a) has a weight-average molecular weight in the range between 10,000 and 400,000 inclusive. .DELTA.n(a)>.DELTA.n(b).times.10 (1) 1<(nx-nz)/(nx-ny) (2) 0.0005.ltoreq..DELTA.n(a).ltoreq.0.5 (3)This optical film can prevent the occurrence of iridescence, the occurrence of cracks, and the occurrence of variation in retardation.