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