Abstract: The present invention provides a refractory composition containing expandable powder that consists of an alkali metal oxide and silicon oxide and is coated onto a steel frame structure of a building or a structure requiring fire prevention or fireproofing in order to prevent the strength or resistance force of the structure from being deteriorated by high-temperature heat in case of fire. The refractory composition of the present invention specifically consists of 1 wt % to 50 wt % of expandable powder composed of silicate, 20 wt % to 80 wt % of silicate binder, 0.05 wt % to 5 wt % of stabilizer, and 0.01 wt % to 10 wt % of fiber.