This invention provides an imaging lens assembly comprising: in order from an object side to an image side: a first lens with positive refractive power having a convex object-side surface and a convex image-side surface; a second lens with negative refractive power having a concave object-side surface; a third lens with positive refractive power having a convex image-side surface, at least one of both surfaces thereof being aspheric; and a fourth lens with negative refractive power having a convex object-side surface and a concave image-side surface on which at least one inflection point is formed; wherein there are four lenses with refractive power, an on-axis spacing between an aperture stop and an electronic sensor provided therein is SL, an on-axis spacing between the object-side surface of the first lens and the electronic sensor is TTL, they satisfy the relation: 0.75