Thermosensitive poly(N-vinylamide) derivatives bearing an oligo ethylene glycol (OEG) chain at the N-position were designed for development of a kinetic hydrate inhibitor (KHI). Novel N-vinylamide monomers bearing an OEG chain at the N-position were synthesized and copolymerized with N-vinylformamide (NVF) or methyl N-vinylacetamide (MNVA) by free radical polymerization. Then, thermosensitive behaviors, such as lower critical solution temperature (LCST), of the synthesized poly(N-vinylamide) derivatives were investigated by light transmittance and DSC measurement. The LCST values were observed over a wide temperature range from 45 to 90 degrees C due to the ethoxy OEG chain at the N-position. Their phase transition properties were investigated under dilute condition by light scattering measurement. Furthermore, KHI values of the synthesized polymers were evaluated by the THF hydrate crystal growth method. On the basis of these results, it is expected that the polymers of synthesized poly(N-vinylamide) derivatives will gain a prominent position in the oil industry.