The present invention relates to a highly heat resistant silsesquioxane-based photosensitive resin composition for a liquid crystal display device or an organic EL display device, and a positive resist insulating layer prepared therefrom, and in particular, to a silsesquioxane-based photosensitive resin composition having high heat resistance and a low dielectric property, capable of being used as an insulating layer forming a via hole of the thin film transistor (TFT), and simultaneously, capable of being used as an insulating layer for forming a bank pattern dividing pixels of an organic EL display device.