The relationship between the viscoelastic properties and instantaneous bending recovery (BR+) was investigated for two different polyester films, PET and PEN. The former, such as a residual modulus (Er) and ratio of elastic strain to total strain applied to films (εel/εtotal), was determined from the stress relaxation-recovery test using a dynamic mechanical analyzer (DMA). The latter was obtained from the radii of curvature of the films before and after bending test. All experiments were carried out at temperature below the glass transition temperature (Tg) of the films. The plots of BR+ vs. Er or εel/εtotal exhibited good correlation, showing that the high magnitude of elastic response or slow relaxation during bending test plays an important role in an improvement of bending recovery. The tentative conclusion was verified for the films which were physically aged below Tg. As the degree of physical aging, which was measured from the enthalpy relaxation endotherms, proceeded, the relaxation behavior became slow and thus significant increase in bending recovery was achieved.