Azobenzene (At) amphiphiles were spread on the water surface. Irradiation of UV and visible light on the floating monolayer caused reversible expansion and contraction of these film, On/off switching of this photoresponse was achieved by chemical stimuli from the water subphase for a monolayer of a carboxylic acid derivative. Using a polymeric Az monolayer, photochemical on/off switching of the "camphor dance" was feasible, which was the consequence of photoinduced changes in the surface pressure at a fixed film area.