An imaging lens assembly includes first, second, third and fourth optical lens elements that are arranged sequentially from an object side to an image side along an optical axis and that respectively have negative, positive, positive and negative refractive powers, and a fixed aperture stop that is disposed between the first and second optical lens elements. The fourth optical lens element has object-side surface and an image-side surface that has at least an inflection point. The imaging lens assembly satisfies the optical condition of 1.8