PURPOSE: To keep temperature of a body tip end at lower one by making use of gas involving a much volume of pure oxygen or oxygen by forming a boundary layer ring in the vicinity of the burner tip end for preventing fine oil particles from being stored.

CONSTITUTION: A burner apparatus 10 includes a discharge conical portion 70 which is located within an outlet end of a fuel mechanism located downstream of a spray member 42. The discharge conical portion 70 is located within an outlet passage of a fuel oil mechanism, ensures an annular passage 78 between the discharge conical portion 70 and a radiation shielding portion 56, forms a boundary layer cooling ring between the radiation shielding portion 56 and the discharge conical portion 70, and discharges spray oil to the neighbourhood of a burner tip end portion 26. The boundary layer cooling ring formed with a medium to spray oil to fine fuel particles cools the radiation shielding portion 56 and the discharge conical portion 70, eliminates lacking in the spray chamber, and prevents a spiral of fine particles from being accumulated on the radiation shielding portion 56 surrounding the burner tip end portion 26.