A focus adjusting optical lens assembly 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 and a fifth lens element. The first lens element with positive refractive power has a convex object-side surface. The second lens element has negative refractive power. The third lens element has refractive power. The fourth lens element with negative refractive power has a concave object-side surface and a convex image-side surface. The fifth lens element with refractive power has a concave image-side surface at a paraxial region, wherein the image-side surface of the fifth lens element changes from concave at the paraxial region to convex at a peripheral region, and both of an object-side surface and the image-side surface of the fifth lens element are aspheric.