A variable focal length lens device includes: a lens system of a liquid resonant type whose refractive index is changed in response to a drive signal to be inputted; a temperature sensor configured to acquire temperature information of the lens system; and a drive controller configured to control the lens system. The drive controller includes: a resonant frequency estimation unit configured to calculate an estimated value of a resonant frequency of the lens system on a basis of the temperature information; and a starting frequency setting unit configured to set a starting frequency of the lens system on a basis of the estimated value of the resonant frequency.