A variable optical element is formed by a first liquid member, a second liquid member which is unsoluble in the first liquid member, a container which contains the first liquid member and the second liquid member, an index for positioning the variable optical element according to a predetermined reference. In the variable optical element, an interfacial shape between the first liquid and the second liquid surface varies according to a voltage which is applied to the liquid members, and the index is disposed such that a wave front aberration in the variable optical element should be minimum or fewer than a predetermined value under condition that the variable optical element is positioned according to the predetermined reference. By doing this, it is possible to restrict the wave front aberration which is caused by a gravity in the variable optical element, the optical unit, and the image capturing device.