The method for producing a solid electrolyte sheet according to the present invention comprises: a first step of applying a first slurry containing a solid electrolyte to a substrate to form a first uncured product; a second step of drying the first uncured product on the substrate to form a first solid electrolyte layer; a third step of applying a second slurry to an upper surface of the first solid electrolyte layer to form a second uncured product; a fourth step of digging a sheet-formed three-dimensional structure into the second uncured product; and a fifth step of drying the second uncured product that has entered inside the three-dimensional structure and the second uncured product that is present on the three-dimensional structure to form a second solid electrolyte layer inside and on the three-dimensional structure, thereby obtaining a solid electrolyte sheet with the second solid electrolyte layer filling inside of the three-dimensional structure.