Base isolation apparatus, lifting apparatus, and base isolation unit

A base isolation unit comprising:

• a vibration-source connector to be connected with a structure or a ground subjected to seismic vibration;
• an isolated-object connector to be connected with an object to be isolated from vibration, the isolated-object connector being disposed movably with respect to the vibration-source connector in a predetermined base isolation direction;
• a lock device disposed between the vibration-source connector and the isolated-object connector and configured to switch between a state of fixing the isolated-object connector with respect to the vibration-source connector and a state of making the isolated-object connector movable;
• a distance recovery device disposed between the vibration-source connector and the isolated-object connector and configured to generate a force for causing an amount of change of a distance between the isolated-object connector and the vibration-source connector to approach zero, depending on the amount of change, the amount of change being a change from the distance in the state in which the lock device fixes the isolated-object connector with respect to the vibration-source connector, the distance recovery device including
• a tensile-side elastic body being subjected to a pressure caused by an external force along the base isolation direction in an orientation of increasing the distance, and
• a compressive-side elastic body being applied with a preload and being subjected to a pressure caused by the external force in an orientation of decreasing the distance;
• and
• a vibration damper disposed between the vibration-source connector and the isolated-object connector and configured to generate a force in the orientation of decreasing the distance as the distance increases, and to generate a force in the orientation of increasing the distance as the distance decreases.