This invention provides a photographing lens assembly comprising, in order from an object side to an image side: a first lens element with positive refractive power having a convex object-side surface and a convex image-side surface; a second lens element with negative refractive power having a concave object-side surface and a concave image-side surface; a third lens element with negative refractive power, the object-side and image-side surfaces thereof being aspheric; a fourth lens element with negative refractive power having a concave image-side surface on which at least one inflection point is formed; and an aperture stop disposed between an imaged object and the second lens element; wherein there are four lens elements with refractive power. Such an arrangement of optical elements can effectively reduce the size of the lens assembly, attenuate the sensitivity of the optical system and enable the lens assembly to obtain higher resolution.