1 MeV Cu2+ ions have been implanted into un-doped ZnO and Ga-doped ZnO films with a dose of 1 x 10(17) ions/cm(2) at room-temperature. Cu ion-implanted Ga-doped ZnO had ferromagnetism at room-temperature and the saturation magnetization of this sample was estimated to be 0.12 mu(B) per Cu, while the Cu ion-implanted un-doped ZnO did not show ferromagnetic behavior. Near-edge X-ray fine structure (NEXAFS) spectroscopy revealed that a partial amount of implanted Cu ions existed as Cu2+ (d(9)) state in Ga-doped ZnO film. On the other hand, almost Cu atoms existed as Cu1+ (d(10)) state in un-doped ZnO film. However, the subsequent annealing at temperature above 800 degrees C on this ferromagnetic sample induced the annihilation of ferromagnetism due to the formation of non-ferromagnetic Cu2O phase. (C) 2012 Published by Elsevier B.V.