We aimed to prepare an elastic nanocapsule by internal modification of a liposome with living radical polymerization. First, monomers and photoiniferters were encapsulated in liposomes. Then, UV light irradiation was used to conduct living radical polymerization in the liposomes. The obtained nanocapsules showed good absorption and retention of chemical substances depending on the binding ability to the incorporated polymers, and the absorption capacity could be controlled by the length and dissolved state of the polymer chains. In addition, dynamic morphological changes in the capsules were observed when liposomes with high membrane fluidity were employed. Morphological changes in the nanocapsules were induced by altering the pH value and ionic strength, resulting in the release of cargo in response to these environmental conditions.