Submillimetre size self-assemblies composed of oleate and azobenzene derivatives show forceful motions such as screwtype coiling-recoiling motion by photoirradiation.In the past half century, many molecular-level machines which 10 change their molecular structure upon exposure to stimuli have been reported. 1 Nowadays, studies on macroscopic thermal motion of soft matters received attentions from the viewpoint of biomimetics. 2,3 Next key step for soft matters is to create a material whose macroscopic motion is controlled by external 15 stimuli. 4 One of the strategies is to create soft materials consisting of subunits sensitive to external inputs, for instance, the photoinduced bending of polymer films consisted of azobenzene derivatives. 5,6 Another strategy is to create soft materials in which macroscopic motions of molecular assemblies 20 are actuated by small amount of molecular machines. 7 To date, there are few reports describing macroscopic mechanical behaviour based on the latter strategy. 8 Here, we report reversible and spatially controlled macroscopic motion of oleate assembles which have submillimetre length. 25Mixtures of oleic acid (1H) and oleate (1 -) ( Fig. 1) are capable of self-assembly in aqueous solution. The morphology of the mixture depends on pH and ionic strength (I). [9][10][11] In I = 0.1 pH 8-10 aqueous media, oleates form vesicles (Fig. 2a). Between pH 7 and 8, they form several complex aggregates called "blocks" that 30 exhibit an inverted hexagonal phase 12 (Fig. 2b). In the transition region, helical and straight multilayer assemblies are coexisted with vesicles and blocks. 11 It is considered that the shape of assembly depends on the ratio of 1H and 1 -in each assembly. According to the microscopic observations of shape and 35 dynamics described in Ref. 11, the helical assemblies are sufficiently flexible to change their macroscopic helical pitch and curvature, but are also elastic because of the highly-ordered stacking structure of oleate molecules in the assembly. As demonstrated in Fig. 3, the helical assemblies exhibit a highly 40 elastic response to mechanical stress. We assumed that this softness and elasticity of the self-assembly is suitable to the spatially moving material in which motion of molecular machine should be propagated.Azobenzene derivatives 2-5 ( Fig. 1) display reversible 2-5 by addition of 70 mM KH 2 PO 4 -K 2 HPO 4 buffer solution (1.0 mL) and sonication for 20 min. A 125 µL aliquot of each suspension containing one of 2-5 was placed in a sealed microscope slide and incubated for 1 day at 25°C. All 60 azobenzene derivatives dissolved into oleate assemblies. The pH range required for formation of helical assemblies was slightly lowered by the addition of 2-5. 14 Helical assemblies were formed when pH 7.3 buffer solution was used as the dispersing medium (the pH of the dispersion was approximately 7.5); pH 65 values of buffer solution higher than 7.3 resulted in vesicle formation, and pH values lower than 7.3 led to the formation of