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 refractive power. The third lens element with refractive power has a concave image-side surface. The fourth lens element has refractive power, and at least one surface thereof 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 a convex object-side surface, and an image-side surface changing from concave at a paraxial region thereof to convex at a peripheral region thereof, and the surfaces are aspheric.