We observed spontaneous shape change of a uniaxially deformed liquid-crystalline elastomer composed of smectic main-chain liquid-crystalline polyesters with varying temperature in a cyclic heating-cooling process. Although the elastomer contracted about 115 % ((L-Liso)/Liso x 100) on heating up to the isotropic phase, the sample length recovered only 55 % on cooling to room temperature in the first heating-cooling process, the elastomer exhibited almost complete reversible deformation in the

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... ond heating-cooling process. By comparison of the sample observation with the X-ray analysis in the cyclic heating-cooling process, we recognized that the stain λ = L / Liso is linearly coupled with the orientational order parameter S. In addition, the