To provide a separator for all-solid-state batteries, which is configured to achieve both increased tensile strength and excellent ion conductivity, a method for producing the same, and an all-solid-state battery comprising the separator for all-solid-state batteries. Disclosed is a separator for all-solid-state batteries, the separator comprising a first solid electrolyte layer comprising a solid electrolyte and a hydrogenated rubber-based resin where a content of the hydrogenated rubber-based resin in the first solid electrolyte layer is 15% by volume or more and 30% by volume or less, and the separator optionally further comprising, on at least one surface of the first solid electrolyte layer, a second solid electrolyte layer comprising a solid electrolyte and a hydrogenated rubber-based resin where a content of the hydrogenated rubber-based resin in the second solid electrolyte layer is 0.1% by volume or more and less than 15% by volume.