A level-variable supporting apparatus is provided, which is so constituted that: a reversible swelling and contractive substance, which, with a prescribed temperature defined as the boundary, absorbs a swelling solution and then swells at a range of temperature on one side and discharges the swelling solution and then contracts at a range of temperature on the other side, is contained in liquidtight container which is expandable and shrinkable in prescribed directions; a liquid guiding portion to supply the swelling solution to the container and discharge it from the container, and a heating means to heat the substance are provided; and the swelling and contraction of the substance due to the change in the temperature of the substance with the prescribed temperature as the boundary causes the container to expand and shrink in the prescribed directions, thus leading to the change of the supporting position of a supported object supported by the container.