To provide an illuminating device in which a liquid lens with a small diameter can be used and which has high illumination efficiency.

An illuminating device includes a light source 11, a convergent lens part 12 having a positive refractive power, and a focus variable lens part 13 capable of changing a focus position while the position of a lens is fixed, in this order. The diameter of a light flux emitted from the light source 11 is converged to a size equal to or smaller than the lens diameter of the focus variable lens part 13 by the convergent lens part 12, and then the light flux is made incident to the focus variable lens part 13.