An all-solid secondary battery includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive electrode layer and the negative electrode layer, wherein the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer includes a lithium-containing sulfide-based positive electrode active material, the lithium-containing sulfide-based positive electrode active material includes Li 2 S, a Li 2 S-containing composite, or a combination thereof, the all-solid secondary battery includes a first inactive member on one surface of the positive electrode layer, the negative electrode layer includes a negative electrode current collector and a first negative electrode active material layer, a ratio of initial charge capacity of the first negative electrode active material layer to an initial charge capacity of the positive electrode active material layer is in a range of about 0.005 to about 0.45.