All-solid-state cells, using sulfur-based cathode materials and Li2S–P2S5 glass-ceramic electrolytes exhibited excellent cycling performance at room temperature. The cathode materials consisting of sulfur and CuS were synthesized by mechanical milling, using a mixture of sulfur and copper crystals with several different molar ratios. The cell performance was influenced by the composition of S/Cu for the cathode materials and the cell with the cathode material of S/Cu = 3 prepared by milling for 15min retained large discharge capacities over 650mAhg−1 for 20 cycles. Sulfur as well as CuS in the cathode materials proved to be utilized as active materials on charge–discharge processes in the all-solid-state batteries.