An imaging lens assembly includes a plastic barrel and an imaging lens set. The plastic barrel includes an object-side aperture and a first annular surface. The imaging lens set includes a plurality of optical elements, wherein at least one of the optical elements is a plastic lens element, and the plastic lens element includes an effective optical portion, a peripheral portion, a second annular surface, and an object-side connecting surface. The peripheral portion is formed around the effective optical portion. The second annular surface is formed on an object-side surface of the plastic lens element and surrounds the effective optical portion. The object-side connecting surface is formed on the object-side surface of the plastic lens element and surrounds the effective optical portion, and the object-side connecting surface is connected with one of the optical elements disposed on an object side of the plastic lens element.