A photographing optical lens system includes, in order from object side to 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 an object-side surface being convex in a paraxial region thereof. The second lens element has refractive power. The third lens element has negative refractive power. The fourth lens element has negative refractive power. The fifth lens element has refractive power. The sixth lens element with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in paraxial region thereof, wherein the image-side surface of the sixth lens element has at least one convex shape in an off-axis region thereof.