Abstract: Disclosed is a thin film aluminum alloy which is limited in the generation of hillocks while maintaining a low specific resistance and hardness irrespective of annealing temperature. In order to obtain the thin film aluminum alloy having a Vickers hardness of 30 Hv or less and a film stress (absolute value indication) of 30 kg/mm2 or less when performing annealing treatment at a temperature ranging from 25° C. to 500° C., wherein said hardness and said film stress are distributed in a predetermined hardness range and in a predetermined film stress range respectively within the temperature range of the above-mentioned annealing treatment and are respectively almost constant against annealing temperature, the thin film aluminum alloy being formed as a film on a substrate by a sputtering method using a sputtering target having a composition comprising 0.5 to 15 atom % of one or more types selected from Ag, Cu, Mg and Zn and 0.