To provide a casting method of a hollow steel ingot in which the air permeability is excellent, a sleeve is prevented from being cracked during the casting, and a core capable of easily separating a sleeve and a core piece from the steel ingot after the casting is used.

In a casting method of a hollow steel ingot in which a mold 1 is installed on surface blocks 9, 10, a core 2 is installed in the mold 1, and a molten steel is poured by the bottom pouring method, a cylindrical non-baked refractory sleeve 3 which mainly consists of MgO and contains organic matters is installed as a core 2, and refractory granules 4 are placed in the sleeve 3 for casting.