Abstract: A surface treatment agent for aluminum heat exchangers, which includes a zirconium element, vanadium element, fluorine element, aluminum element and an acrylic polymer, with the concentration of zirconium element in terms of zirconium being 100-100,000 ppm by mass, the concentration of vanadium element in terms of vanadium being 50-100,000 ppm by mass, the fluorine element concentration being 125-125,000 ppm by mass, the concentration of aluminum element in terms of aluminum being 5-10,000 ppm by mass and the concentration of the acrylic polymer being 100-100,000 ppm by mass. The surface treatment agent has a pH of 0.5-3, and suppresses odor generated from an aluminum heat exchanger, and the generation of white rust that deposits on the surface of an aluminum fin.