The variable liquid device includes: a chamber including a channel, in which a fluid flows, having an inconsistent height in at least a part of the channel; a first fluid filled in the chamber and formed of a non-transmissive material; and a second fluid filled in the chamber and formed of a light transmittable material that does not mix with the first fluid, wherein an aperture, through which light is transmitted, is adjusted according to a variation of an interface between the first fluid and the second fluid.