The present disclosure provides a photographing optical lens system comprising five lens elements, the five lens elements being, in order from an object side to an image side: a first lens element with positive refractive power having an object-side surface being convex in a paraxial region thereof, a second lens element having positive refractive power, a third lens element having negative refractive power, a fourth lens element having positive refractive power, and a fifth lens element with negative refractive power having an image-side surface being concave in a paraxial region thereof with at least one convex critical point in an off-axial region thereof, both of an object-side surface and the image-side surface thereof being aspheric.