To provide an irregular refractory material which can be sintered at <1300°C and develops its strength.

This basic irregular refractory material contains 50 to 98 wt.% of MgO component and the balance of two or more kinds of other components selected from Al2O3, B2O3, CaO, FeO, MgO, MnO, P2O5 and SiO2, and an inevitable impurity component. A part or the whole of the magnesia intergranular region produces a liquid phase at 500 to 1400°C. Further, the irregular refractory material contains zirconia, zircon, carbon, carbide, boride, nitride or metals. Other components consists of, by weight ratio, SiO2:CaO=35:55 to 80:20, Al2O3: CaO=60:30 to 30:60, SiO2:Al2O3=85:15 to 50:50, FeO:SiO2=100:0 to 35:55. MnO: SiO2=80:20 to 50:50, P2O5:CaO=100:0 to 50:50, P2O5:Al2O3=80:20 to 70:30 and P2O5:SiO2=100:0 to 5:95, and are included in total by 2 to 30 wt.%. Or, the material contains B2O3 and SiO2 in total by 2 to 30 wt.% in a weight ratio, of B2O3:SiO2=100:0 to 5:95, and contains 70 to 98 wt.% of MgO. The obtd. basic irregular refractory material is used for the kiln.