By precisely arranging mechanically interlocked "catenane" molecules three-dimensionally, we succeeded in developing soft crystals.  By heating a solution containing catenane molecules and cobalt ions, single crystals were prepared.  Single crystal X-ray analysis revealed that more than 90wt% of the crystal is made up of catenane molecules, and that countless micropores are formed in the crystal.  Furthermore, the crystal changes its shape when an external force is applied to it and returns to its original shape when the force is removed, indicating that the crystal has rubber-like properties.  We believe that this elastic crystal leads to innovative porous materials that can absorb and desorb gas molecules such as carbon dioxide.