To provide an imaging lens device with which downsizing is attained by shortening of a back focus while the high performance to satisfy high sharpness in a zoom lens system is assured.

The imaging lens device is equipped with a zoom lens system TL which performs variable magnification by changing the spacing between lens groups and an imaging element SR which changes the optical image formed by the zoom lens system TL to an electrical signal. The zoom lens system TL consists of three components; successively from an object side, a first lens group GR 1 having negative optical power, a second lens group GR 2 having positive optical power, and a third lens group GR 3 having positive optical power and satisfies a conditional expression: 0.1<Bf/Y'<1.0, where Bf: the axial distance from a final lens face up to an image plane (the shortest axial distance among respective zoom positions in the case the final lens in the variable magnification is movable), and Y': half the diagonal angle of the imaging plane.