Cu 2 Sn 1-x Ge x S 3 (CTGS), which has characteristics suitable for the light absorption layer of single junction solar cells and is expected because an abundant and non-toxic element, was deposited by the sol-gel sulfurization method. The main peak of the sample sulfurized at 600 °C shifted by 0.44°to the higher angle side from Cu 2 SnS 3 (200) (CTS). From the peak shift angle, the chemical composition ratio of Ge/(Sn+Ge) was estimated to be 0.57. From SEM and EPMA results, Sn was evaporated from the film surface at high temperature during a sulfurization process. Therefore, the film surface became Ge-rich. From the results of Raman spectrum observation, CTGS near the substrate contained graphite. The band gap energy inferred from the (ahν) 2 -plots was lower than the reported band gap energy of CTGS. The lower band gap energy was considered to be due to the lower graphite-rich layer.