A phase difference film which comprises a liquid crystal film having a liquid crystal comprised of a cellulose derivative as a liquid crystal compound (cellulose derivative liquid crystal) being oriented in a specific direction, preferably said phase difference film wherein said orientation in a specific direction is fixed. In said liquid crystal film, through changing appropriately the molecular weight of the cellulose derivative, the composition of the liquid crystal, the degree of the orientation, and the like, films having various wave length dispersion characteristics can be prepared with ease, and further a phase difference film satisfying the following relationship: .DELTA.n450=.DELTA.n550=.DELTA.n650 (1) wherein .DELTA.n550 represents a double refractive index at a wave length of 550 nm, .DELTA.n450 represents a double refractive index at a wave length of 450 nm, and .DELTA.n650 represents a double refractive index at a wave length of 650 nm, can be prepared without laminating a plurality of phase difference films. Said phase difference film, used in combination with a polarizing film, exhibits excellent reflection preventing effect, contrast improving effect, double refraction compensating effect, and the like.