In order to develop highly functional hydrogel materials, elaborate design and precision construction of network structure are required. To this end, we are focusing on controlled/living radical polymerization techniques not only to synthesize defined precursor polymers but also to give a unique function by reversible activation-deactivation reaction mechanism. In this paper, a feature of living radical polymerization for gel synthesis is briefly described, and our recent results are outlined. In particular, the design of self-healable gel utilizing reversible addition-fragmentation chain transfer (RAFT) polymerization mechanism and amphiphilic conetworks with crosslinked domains capable of unique thermoresponsive swelling behavior and mechanical toughening are presented.