Transparent polyimides (TPIs) have a possibility for the using of foldable displays because of their enhanced flex resistance and high thermal stability. On the other hand, TPIs have high birefringence (= high out of plane retardation (Rth)) thus it causes the rainbow mura if when a display using a conventional TPI film was watched through polarized sunglasses. It was reported that optical films were decreased the retardation by doping with inorganic crystals, that have rod-shaped and the opposite birefringence to that of the polymers. However, if particle size and amount of added crystals are not optimized, its haze values are increased. The purpose of this article is to fabricate the low retardation TPI films with inorganic birefringent crystals such as strontium carbonate (SrCO3) crystals with their rod-like shape and opposite birefringence. We found small and nearly monodispersed SrCO3 suggested low Rth of 17 nm and low haze TPI films. The Rth value of this film is almost same of triacetylcellulose film, which is widely used in display as low retardation film. This low retardation film was obtained by casting method from the under 100 nm SrCO3 dispersed TPI solution.