A burner equipped with: a tubular first outer tube (20); a diffuser (21) arranged on the inside of the first outer tube (20) and having an inner circumferential surface the diameter of which gradually increases in a first direction; first gas nozzles (22) that supply a first gas toward the first direction in a region on the outside of the diffuser (21) in the radial direction; second gas nozzles (23) that are arranged adjacent to the first gas nozzles (22) in the circumferential direction of the first outer tube (20), and that supply a second gas toward the first direction in the region on the outside of the diffuser (21) in the radial direction; and an ignition torch (24) that ignites the second gas and/or the first gas.
