To provide a burner which can be downsized, easily manufactured without generating secular machine errors and change of a swirl flow.

The burner 21 is equipped with a wind box 22 provided to face to a burner throat 2 installed on a furnace wall 1, a cylindrical nozzle body 30 on a central axis of the burner throat 2, and a secondary air adjustment device 32 on an end of the nozzle body 30. The secondary air adjustment device 32 is composed of a circular partition plate 33 forming an air intake port around the nozzle body 30 between the burner throat 2 and itself, a movable vane holder 35 movably provided in the axial direction of the nozzle body 30, and movable vanes 36 arranged for the movable vane holder at predetermined intervals around the partition plate 33 for swirling the passing secondary air. The secondary air adjustment device 32 is moved back and forth to change a covering state of the movable vanes 36 for the air intake port, allowing adjustment of the swirl flow of air flowing in the burner throat 2.