Provided is a film formed by stabilizing the cholesteric liquid crystal phase of a membrane formed from a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound, wherein the helical pitch of the cholesteric liquid crystal phase in the thickness direction of the film undergoes a change that satisfies Formula 1 and Formula 2 within one layer. When this film is incorporated in a liquid crystal display device the frontal luminance can be increased, oblique-angle color changes can be suppressed, and the number of stacked layers is small. Also provided are a film manufacturing method, a luminance-enhancing film, an optical sheet member, and a liquid crystal display device. Formula 1: ΔP/Δs<0 Formula 2: ΔP/Δs>0 In Formula 1 and Formula 2, ΔP represents the minimum amount of change in the helical pitch of the cholesteric liquid crystal phase, and Δs represents the minimum amount of change in the distance from one surface of the film, in the thickness direction of the film.
