Liquid for liquid lens and liquid lens

A second liquid for a liquid for liquid lenses which is used in combination with a conductive aqueous solution serving as a first liquid and which separates from the first liquid to form an interface. The liquid for liquid lenses contains an alkylnaphthalene compound. The alkylnaphthalate compound to be used as the second liquid for the liquid for liquid lenses preferably has a C 1-4 alkyl group as the alkyl group. When the naphthalene compound has an alkyl group having more than five carbon atoms, it has a reduced refractive index and is solid at use temperatures. The alkyl group preferably is methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, or tert-butyl.