A surface treatment method for aluminum heat exchangers including (a) a step wherein a chemical conversion coating film is formed on the surface of an aluminum heat exchanger by subjecting the aluminum heat exchanger to chemical conversion using a chemical conversion agent; (b) a step wherein the aluminum heat exchanger, the surface of which has been provided with a chemical conversion coating film in step (a), is brought into contact with a hydrophilizing agent that contains a hydrophilic resin; and (c) a step wherein a hydrophilized coating film is formed on the surface of the aluminum heat exchanger by baking the aluminum heat exchanger, which has been subjected to a contact treatment in step (b). The chemical conversion agent used in step (a) contains zirconium and/or titanium in an amount of 5-5,000 ppm by mass in total, vanadium in an amount of 10-1,000 ppm by mass and a metal stabilizer in an amount of 5-5,000 ppm by mass. In addition, the chemical conversion agent used in step (a) has a pH of 2-6.