An imaging lens set includes a plastic lens element. The plastic lens element having a central axis includes an object-side surface and an image-side surface, wherein the image-side surface is located opposite to the object-side surface. Each of the object-side surface and the image-side surface includes an effective optical section and a lens peripheral section in order from the central axis to an edge of the plastic lens element. The effective optical section is for being passed through by an imaging light and aspheric. The lens peripheral section surrounds the effective optical section. At least one of the lens peripheral section of the object-side surface and the lens peripheral section of the image-side surface includes at least one annular groove structure, wherein the annular groove structure includes a plurality of stepped surfaces and is not in contact with the optical elements.