The present invention relates to a polyimide-based film, a window cover film including the polyimide-based film, and a display panel including the polyimide-based film. More specifically, the present invention relates to a polyimide-based film of which a modulus measured according to ASTM D882 is 5 GPa or more and a rate of change of the modulus, after the polyimide-based film is maintained under a high-temperature and high-humidity condition of 60° C. and 90% RH for 500 hours, is 10% or less.