A main object of the present disclosure is to provide an all-solid-state battery with an excellent capacity durability. The present disclosure achieve the object by providing an all-solid-state battery comprising: a cathode active material layer, an anode active material layer, and a solid electrolyte layer formed between the cathode active material layer and the anode active material layer; wherein at least one of the cathode active material layer and the anode active material layer contains a sulfide solid electrolyte and a conductive auxiliary material; the conductive auxiliary material includes a carbon material C1 having a carboxyl group on its surface; and a weight ratio of the carboxyl group to overall of the carbon material C1 is 8 weight % or more.