PURPOSE: To improve recording and reproducing characteristics by forming a recording layer on one side of a laminated film obtd. by forming coating layers on both sides of a polyester film and having ≤3% variation (ΔH) of film turbidity.

CONSTITUTION: A recording layer is formed on one side of a laminated film obtd. by forming coating layers on both sides of a polyester film. The variation (ΔH) of film turbidity of the laminated film is represented by an equation ΔH=H1-H2 (where H1 is the turbidity of the film after heat treatment at 170°C for 30min and H2 is the turbidity of the film at ordinary temp. before the heat treatment) and the variation (ΔH) is ≤3%. The optical tape having satisfactory optical recording and reproducing characteristics is obtd.