A nozzle structure (10, 20, 30) for a hydrogen gas burner apparatus, comprising: an outer tube; an inner tube concentrically disposed inside the outer tube, and a gas blowing part disposed at an end part of the outer tube, the gas blowing part including an oxygen-containing gas blowing duct and a hydrogen gas blowing duct; wherein the outer tube is arranged to extend beyond an opened end of the inner tube in an axial direction, the opened end arranged at the other end of the inner tube to the end part of the outer tube, to form a space between an inner circumferential surface of the outer tube and an outer circumferential surface of the inner tube, wherein the oxygen-containing gas blowing duct is configured to blow out an oxygen-containing gas in the axial direction such that the oxygen-containing gas passes through a space inside the inner tube at a first flow velocity (Va) so that the oxygen-containing gas is discharged from the opened end of the inner tube in the axial direction and such that the oxygen-containing gas proceeds inside of the part of the outer tube that extends beyond the opened end towards an end part of the outer tube, the hydrogen gas blowing duct is configured to blow out a hydrogen gas into the space between the inner circumferential surface of the outer tube and the outer circumferential surface of the inner tube in the axial direction such that the hydrogen gas passes through the space between the inner circumferential surface of the outer tube and the outer circumferential surface of the inner tube at a second flow velocity (Vh), is discharged from said space in a direction parallel to the axis, and proceeds along the outer periphery of the oxygen-containing gas. an outer tube; an inner tube concentrically disposed inside the outer tube, and a gas blowing part disposed at an end part of the outer tube, the gas blowing part including an oxygen-containing gas blowing duct and a hydrogen gas blowing duct; wherein the outer tube is arranged to extend beyond an opened end of the inner tube in an axial direction, the opened end arranged at the other end of the inner tube to the end part of the outer tube, to form a space between an inner circumferential surface of the outer tube and an outer circumferential surface of the inner tube, wherein the oxygen-containing gas blowing duct is configured to blow out an oxygen-containing gas in the axial direction such that the oxygen-containing gas passes through a space inside the inner tube at a first flow velocity (Va) so that the oxygen-containing gas is discharged from the opened end of the inner tube in the axial direction and such that the oxygen-containing gas proceeds inside of the part of the outer tube that extends beyond the opened end towards an end part of the outer tube, the hydrogen gas blowing duct is configured to blow out a hydrogen gas into the space between the inner circumferential surface of the outer tube and the outer circumferential surface of the inner tube in the axial direction such that the hydrogen gas passes through the space between the inner circumferential surface of the outer tube and the outer circumferential surface of the inner tube at a second flow velocity (Vh), is discharged from said space in a direction parallel to the axis, and proceeds along the outer periphery of the oxygen-containing gas.