<p>A burner includes a tubular inner tube portion (33) and a tubular outer tube portion (31). The inner tube portion (33) mixes fuel with air. The outer tube portion (31) surrounds the inner tube portion (33). A peripheral wall of the inner tube portion (33) has a gaseous mixture outflow hole (42). The gaseous mixture outflow hole (42) causes a clearance between an inner peripheral surface of the outer tube portion (31) and an outer peripheral surface of the inner tube portion (33) to communicate with an interior of the inner tube portion. A peripheral wall of the outer tube portion (31) has an air supplying hole (31 h). The air supplying hole (31 h) further supplies air to the clearance.</p>
