A photographing optical lens system (1-10; 132; 142; 152; 162) comprising five lens elements, the five lens elements being, in order from an object side to an image side along an optical path: a first lens element, a second lens element, a third lens element, a fourth lens element and a fifth lens element, each of the five lens elements having an object-side surface facing the object side and an image-side surface facing the image side: wherein the first lens element has positive refractive power, the object-side surface of the first lens element is convex in a paraxial region thereof, the image-side surface of the first lens element is convex in a paraxial region thereof, the second lens element has negative refractive power, the image-side surface of the second lens element is concave in a paraxial region thereof, the image-side surface of the third lens element is convex in a paraxial region thereof, the object-side surface of the fourth lens element is convex in a paraxial region thereof, the fifth lens element has negative refractive power, the object-side surface of the fifth lens element is convex in a paraxial region thereof, and the image-side surface of the fifth lens element is concave in a paraxial region thereof, wherein a curvature radius of the object-side surface of the first lens element is R1, a curvature radius of the image-side surface of the first lens element is R2, a curvature radius of the object-side surface of the second lens element is R3, a curvature radius of the image-side surface of the second lens element is R4, an axial distance between the object-side surface of the first lens element and the image-side surface of the fifth lens element along the optical path is Td, an axial distance between the image-side surface of the fifth lens element and an image surface along the optical path is BL, a focal length of the photographing optical lens system is f, a curvature radius of the object-side surface of the fifth lens element is R9, a curvature radius of the image-side surface of the fifth lens element is R10, and the following conditions are satisfied: − 0.80 < R 1 + R 2 / R 1 − R 2; 0 < R 3 + R 4 / R 3 − R 4; Td / BL < 2.0; characterized in that a central thickness of the first lens element along the optical path is CT1, an axial distance between the object-side surface of the fourth lens element and the image-side surface of the fifth lens element along the optical path is Dr7r10, and the following conditions are satisfied: 3.50 < f / R 9 + f / R 10; and 1.0 < CT 1 / Dr 7 r 10. wherein the first lens element has positive refractive power, the object-side surface of the first lens element is convex in a paraxial region thereof, the image-side surface of the first lens element is convex in a paraxial region thereof, the second lens element has negative refractive power, the image-side surface of the second lens element is concave in a paraxial region thereof, the image-side surface of the third lens element is convex in a paraxial region thereof, the object-side surface of the fourth lens element is convex in a paraxial region thereof, the fifth lens element has negative refractive power, the object-side surface of the fifth lens element is convex in a paraxial region thereof, and the image-side surface of the fifth lens element is concave in a paraxial region thereof, wherein a curvature radius of the object-side surface of the first lens element is R1, a curvature radius of the image-side surface of the first lens element is R2, a curvature radius of the object-side surface of the second lens element is R3, a curvature radius of the image-side surface of the second lens element is R4, an axial distance between the object-side surface of the first lens element and the image-side surface of the fifth lens element along the optical path is Td, an axial distance between the image-side surface of the fifth lens element and an image surface along the optical path is BL, a focal length of the photographing optical lens system is f, a curvature radius of the object-side surface of the fifth lens element is R9, a curvature radius of the image-side surface of the fifth lens element is R10, and the following conditions are satisfied: − 0.80 < R 1 + R 2 / R 1 − R 2; 0 < R 3 + R 4 / R 3 − R 4; Td / BL < 2.0; characterized in that a central thickness of the first lens element along the optical path is CT1, an axial distance between the object-side surface of the fourth lens element and the image-side surface of the fifth lens element along the optical path is Dr7r10, and the following conditions are satisfied: 3.50 < f / R 9 + f / R 10; and 1.0 < CT 1 / Dr 7 r 10.