A low-production-cost refractory structure for protecting a water tube in which a refractory tile provided for protecting water tubes being arranged in a boiler, or the like, can be set easily and surely even at such a part as the refractory tile can not be slid on the outer surface of the water tube and jointed. The refractory structure comprises, as a refractory tile engaging member projecting from the water tube 10 side, a supporting member 15 having cross-sectional area smaller at the base part than at the forward end part, and a refractory tile side recess 14 engaging with the supporting member and having cross-sectional area larger than that at the forward end part of the supporting member and movable in the direction toward or away from the supporting member, characterized in that they are bonded through adhesive 12, e.g. mortar, and the forward end part and the base part of the supporting member 15 are formed through a step part or an inclining part.