A nozzle refractory for casting comprising a refractory aggregate which contains 20 mass % or more, relative to the total composition, of a CaO component and 10 mass % or more of a clinker containing CaO as a mineral phase, wherein the coating film of CaCO3 is formed from at least a part of CaO exposed on the surface of particles of the clinker containing CaO as a mineral phase. CaCO3, which forms a film, is decomposed by heat to release a CO2 gas, which makes an operating surface smoother, resulting in no deposition of a metal and thus in the successive supply of CaO to the alumina deposited on the operating surface, which leads to the prevention of the deposition of alumina. The refractory is also effective for preventing the hydration by a hydrolysis reaction.