To provide a burner capable of completely burning a fuel even if it is vegetative regenerated fuel.

This burner 1 comprises a fuel feeder 2, a lower preheater 3 for forming a primary combustion air swirl flow, a primary combustion part 4 for performing primary combustion, a secondary combustion part 5 for performing secondary combustion, and an exhaust cylinder 6. The primary and secondary combustion parts 4, 5 comprise cylindrical first and second combustion chambers 47, 57 and cylindrical annular first and second preheating chambers 46, 56, respectively. The upper parts of the secondary combustion chambers and the second preheating chambers communicate with each other through first and second communication parts, respectively. First and second cylindrical projections 49, 59 project downward from first and second partition plates 44, 45 which partition the upper side surfaces of the second communication parts 48, 58. The primary and secondary combustion airs spirally flowing through the first and second preheating chambers 46, 56 are divided into downward swirl flows F12, F22 flowing toward the lower parts of the first and second combustion chambers 47, 57 and upward swirl flows F13, F23 flowing upward of the first and second combustion chambers 47, 57 by the first and second cylindrical projections 49, 59.