Abstract: AgGaTe2, a chalcopyrite I-III-VI2 compound, has a band gap energy close to that of sunlight and exhibits a high optical absorption coefficient. It is also attracting attention as an environmentally friendly material because it does not contain Se nor Cd and less In. AgGaTe2 thin films have been formed by the close-space sublimation method and fabricated into solar cell devices with a structure of Glass/Mo/p- AgGaTe2 /n-ZnIn2S4 /ZnO: Al. In the past, the close-space sublimation method was performed using Ga2Te3 powder source, and the obtained AgGaTe2 layer was about 20% Te-rich from the stoichiometry. AgGaTe2 thin films with near stoichiometry could be formed when the source was replaced with GaTe powder. Tuning the AgGaTe2 thin film from stoichiometric to Ga-rich composition would lead to higher conversion efficiencies. Therefore, two methods of achieving Ga-rich AgGaTe2 thin films were examined. After thin films were formed, X-ray diffraction θ-2θ measurements were performed. When diffusion/deposition time was increased from 10 to 45 minutes, the FWHM of the AgGaTe2 peak around 24.9°was increased, and the Ga-rich AgGa5Te8 peak appeared, with 30% of the AgGaTe2 diffraction intensity. Extension of diffusion/deposition times as well as the use of Ga:Te = 80:20 source materials were effective to fabricate Ga-rich AgGaTe2 thin films, and the use of these film were effective to increase the efficiency of AgGaTe2 solar cell