Since polymers of cyclic topology have no main chain terminus, and the conformation is limited, they show physical and chemical properties different from those of linear polymers even the composition and molecular weight are the same. In order to pursue functions based on the topology of polymers, we have developed synthetic methods for cyclic polymers and constructed nanostructures by self-assembly. As a result, it was found that micelles and vesicles formed by cyclic polymers exhibit characteristics, which were greatly changed as compared with those of linear polymers. Based on cyclic-to-linear transformation, a gelling agent was developed, and furthermore, the reversible and repeatable topological conversion was achieved. Moreover, monolayer assemblies such as self-assembled monolayers on a gold surface and Langmuir–Blodgett films were constructed from cyclic macromolecules.