SOLID ELECTROLYTE, ELECTROLYTE LAYER AND BATTERY

A solid electrolyte having high electrical conductivity even in a low-temperature region is provided. A solid electrolyte containing a hexagonal perovskite-related compound, in which the compound is a compound represented by the following general formula (1), and an electrolyte layer and a battery using the solid electrolyte are disclosed. BaNbMoMO ...(1), [in the formula (1), M is a cation of at least one element; α represents a Ba deficiency amount and represents a value of 0 or more and 0.5 or less, x represents a value of -1.1 or more and 1.1 or less, y represents a value of 0 or more and 1.1 or less, and z represents an oxygen non-stoichiometry and represents a value of -2.0 or more and 2.0 or less, provided that in the formula (1), |x| + y ≥ 0.01 is satisfied].