Hie synthesized the G4-48Azo dendrimer functionlized. with azobenzene groups, fully reversible photo-isomerization -reaction, in. their periphery. We investigated monolayer behaviour and its characteristics at air-water interface by LB method. And we observed the difference of molecular behaviour and measured the surface pressure shift by 365/nm/ light irradiation. because of the photo-isomerization. of the azobunzene group in their periphery. The electrical properties ofthe G4-48Azo dendrimer were compared with between, trans form and cis form. LB film/metal (MIM) structure and STM system. And we obtained the differences of values in I- V characteristics using STM originating . the photo-isomerization, of the azobenzene.