Polymers containing azobenzene moieties have been attracted considerale interest, mainly because of their potential use of as photoresponsive system. In particular condition, in fact, the trans ⇔ cis photoisomerization of the azobenzene groups can be accompanied by reversible variations of macromolecular conformation and physical propertied of polymers. Recently, poly(L-glutamate) containing azobenzene units (PAZLG) has been reported to undergo a reversible aggregation-disaggregation process upon exposure to light or dark condition. If the terminal hydrogen of azobenzene unit was substituted for the long alkyl chain, the aggregation-disaggregation process of PAZLG would be strongly accelerated with the enhancement of hydrophobic interaction between the azobenzene units in side chain. In this study, we synthesized the photochromic PAZnLG with long alkyl chain (n: the number of methylene group) and evaluatedtheir photomechanical response to ultraviolet (UV) light irradiation.