Abstract: Provided are: an ion-conductive solid which can be produced by heat treatment at a low temperature and which has high ion conductivity; and, an all-solid-state battery having the ion-conductive solid. An ion-conductive solid containing an oxide represented by the general formula Li6-3a-2b-c-dYi1-c-dAlaMgbZrcCedB3O9; and, an all-solid-state battery having at least a positive electrode, a negative electrode, and an electrolyte, at least one element selected from the group consisting of the positive electrode, the negative electrode, and the electrolyte containing the ion-conductive solid (In the formula, a is such that 0.000?a?0.800, b is such that 0.000?b?0.800, c is such that 0.000?c?0.400, d is such that 0.000?d?0.400, and a and b are real numbers satisfying 0.005?a+b?0.800.).

Abstract: An ion conductive solid comprising an oxide represented by general formula: Li6-x-y-2zY1-x-y-zM1xM2yM3zB3O9 in formula, M1 and M2 are each independently at least one metal element selected from a group of Zr, Ce and Sn, M3 is Nb, and x, y, and z represent real numbers satisfying 0.000?x+y<1.000, 0.000?z?1.000, and 0.000<x+y+z<1.000.