The present invention provides a birefringent optical film having a high
orientation for easily obtaining a desired retardation value and also a
small photoelastic coefficient. The birefringent optical film includes at
least two kinds of polymer materials. A total of products of Cn and Wn
satisfies a numerical formula (1):
.SIGMA.(Cn.times.Wn).ltoreq.30.times.10.sup.-8 cm.sup.2/N (1) where Cn
and Wn denote respectively a photoelastic coefficient and a volume
fraction of each polymer material, and at least one of the polymer
materials of the film has a photoelastic coefficient value of at least
60.times.10.sup.-8 cm.sup.2/N.