Conventional bio-degradable polymers have been successfully developed but the control of degradation is indispensable for actual application as useful materials in sustainable society. Here biomonomer having multifunctional structure such as itaconic acid (IA) which has two carboxyls and double bond and whose bioavailability was very high.was used for Nylon development. But IA polymerization was very difficult and the polycondensation of IA to prepare the polyamide structure was not reported as scientific paper. We have prepared IA-derived Nylon via salt-type monomers composed of diacidic IA and diamines. These salts thermally converted into Nylon in the presence of phosphate catalysts to create a pyrrolidone ring in the polymer backbone. The Nylon have thermally softening temperature and mechanical strength higher than conventional Nylon’s. In addition, the polyamides became soluble in water by ring-opening reaction of the pyrrolidone. Actually, the ring-opening reaction was induced by ultra-violet irradiation and landfill in environmental soil as well as alkaline hydrolysis. Especially photo-induced water-solubilization is very important for development of environmentally-corrosive fish line to avoid the ghost-fishing destroying the ecological system around ocean.