A lighting device for an electronic endoscope system, includes a light source; a set of rotary shutters having at least two rotary shutters, having a rotational axis parallel to an optical axis of the light source, the rotary shutters alternately intercepting incident illuminating light emitted from the light source and allowing the incident illuminating light to pass through the set of rotary shutters to proceed toward a light guide, wherein the rotary shutters are associated with each other to be capable of integrally rotating about the rotational axis, each of the rotary shutters having at least one light-shielding portion and at least one opening; and an adjusting device which rotates one of the rotary shutters relative to the other to change an opening angle of each opening to adjust an amount of illuminating light which passes through the set of rotary shutters.