An image capturing lens system includes four lens elements with refractive power, in order from an object side to an image side, a first lens element, a second lens element, a third lens element and a fourth lens element. The positive first lens element has a convex object-side surface at a paraxial region. The negative second lens element has a concave object-side surface at a paraxial region and an image-side surface changing from concave at a paraxial region to convex at a peripheral region, wherein the surfaces of the second lens element are aspheric. The positive third lens element has a concave object-side surface at a paraxial region and a convex image-side surface at a paraxial region. The negative fourth lens element has an image-side surface changing from concave at a paraxial region to convex at a peripheral region, and the surfaces of the fourth lens element are aspheric.