We report novel nanoporous polyimides formed from jungle-gym-type rigid polyimide gels by supercritical CO2 drying. By virtue of supercritical CO2 drying to avoid the collapse of nanostructure, porosity above 90 vol.-% was achieved. We found a rich variety of nanoporous structures in the range of 50-800 nm such as crisp fragments, minute network, and highly-connected beads. These characteristic structures were formed by the competitive progress of liquid-liquid phase separation and crystallization induced due to the two chemical reactions of end-crosslinking and thermal imidization during gelation.