This invention provides an imaging lens assembly including, in order from an object side to an image side: a first lens with positive refractive power having a convex object-side surface; a second lens with negative refractive power having a convex image-side surface; a third lens having a concave object-side surface and a convex image-side surface, at least one of both surfaces thereof being aspheric; a fourth lens having a concave image-side surface, at least one of both surfaces thereof having at least one inflection point; and an aperture stop disposed between an imaged object and the second lens; the on-axis spacing between the first lens and second lens is T12, the focal length of the imaging lens assembly is f, the Abbe number of the first lens and third lens is, V1 and V3, respectively, they satisfy the relations: 0.5