The present disclosure provides an imaging optical lens assembly, including, in order from an object side to an image side: a first lens element with negative refractive power having an object-side surface being concave in a paraxial region, a second lens element with positive refractive power, a third lens element with negative refractive power, a fourth lens element with positive refractive power, and a fifth lens element with negative refractive power having an image-side surface being concave in a paraxial region and at least one convex shape in an off-axial region on the image-side surface, wherein the imaging optical lens assembly has a total of five lens elements.