An optical device and a lens unit each include a liquid container containing an insulating liquid and an electroconductive liquid which are mutually immiscible and optically transparent and have different refractive indices. The optical device and the lens unit also have a gas-absorbing material in or around the liquid container. The gas-absorbing material absorbs gas generated by energization. The optical device and the lens unit can maintain their optical characteristics even if voltage is repeatedly applied. An imaging apparatus includes an optical shooting system having the optical device. The imaging apparatus takes pictures by capturing object light coming through the optical shooting system.