A zoom lens system includes a zoom base to which an image pickup device can be coupled, a driving source for generating rotational force in accordance with a control signal of a control unit disposed in the electronic facility, plural power transmission gears disposed on the zoom base to reduce the rotational force of the driving source, a first lens cam disposed on the zoom base and rotated by the rotational force of the power transmission gears, plural first lens shafts coupled on the zoom base in a direction of an optical axis and located in the first lens cam, a first lens barrel having a first lens, the first lens barrel being disposed in the first lens cam and slidably coupled to the first lens shaft in the direction of the optical axis so as to move in the direction of the optical axis in accordance with rotation of the first lens cam, a power transmission member coupled to the first lens cam in the direction of the optical axis, an outer second lens cam disposed on an outer circumference of the first lens cam and fixed on the zoom base, an inner second lens cam disposed in the outer lens cam and rotating and moving linearly by the power transmission member, plural second lens shafts coupled to the zoom base in the direction of the optical axis and located in the inner second lens cam, and a second lens barrel having a second lens and being disposed in the inner second lens cam and slidably coupled to the second lens shaft to linearly move in the direction of the optical axis in accordance with rotation of the inner second lens cam.