An imging lens device has a zoom lens system and an imaging sensor. The zoom
lens
system has a plurality of lens units and changes gaps between the lens units to
thereby generate an optical image of an object which can be optically and successively
zoomed in and out. The imaging sensor which converts an optical image generated
by the zoom lens system into an electric signal. The zoom lens system comprises,
from the object side, a first unit having a negative power, a second unit having
a positive power, the second unit having a cemented lens element joining three
lens elements, and a lens element having a positive power, a third unit having
a positive power, and an aperture stop disposed between the first unit and the
second unit. Among the three lens elements which form the cemented lens element,
a lens element disposed on the object side directs a convex surface toward the
object side while a lens elements disposed on the image side directs a concave
surface toward the image side. The zoom lens system is fulfilled the predetermined conditions.
