To successfully prevent the leakage of molten steel poured in a mold.

In the starting method of the casting in the bloom continuous casting, with which a T-bar 4 is fitted to a dummy bar head 2 inserted into the mold 1 for continuous casting and also, a cooling member 10 is disposed to the T-bar 4 and successively, the molten steel is poured into the mold 1 and after cooling and solidifying the molten steel abutted on the cooling member 10, the dummy bar is drawn out together with a cast bloom, plural pieces of annular plates 12 having continuous plane are fitted to outside of the T-bar and each of the annular plates 12 is disposed with a prescribed interval in the axial direction of the T-bar 4 and in this way, the cooling member 10 is constituted.