Provided is a method for treating a battery member by which a cathode active material and a sulfide solid electrolyte material can be efficiently separated and Li contained in the cathode active material and the sulfide solid electrolyte material can be efficiently recovered. A method for treating a battery member containing at least a cathode active material containing Li and a sulfide solid electrolyte material containing Li is characterized by comprising a contact step of bringing the battery member and a treatment solution into contact with each other to generate hydrogen sulfide and dissolve Li contained in the sulfide solid electrolyte material in the treatment solution, and a cathode active material recovery step of recovering the cathode active material that is an insoluble component from the treatment solution in which Li is dissolved, and a Li compound recovery step of recovering a Li compound from the treatment solution from which the cathode active material that is the insoluble component is recovered.