The present invention provides an imaging device including a photographic optical system having a zoom function, an auxiliary light irradiation device which includes an auxiliary light source emitting auxiliary light and which irradiates the auxiliary light towards a subject, a range finding device which makes the auxiliary light reflected by the subject incident on the photographic optical system to perform a focusing operation, and an auxiliary light control device which controls at least one of emitted light quantity of the auxiliary light and irradiation range of the auxiliary light in accordance with a zoom position of the photographic optical system.