A burner injects a mixture of fuel and air from a base end side far from a combustion chamber toward a distal end side close to the combustion chamber. The burner has a fuel passage having a turn-back part turning back and channeling the fuel between the base end side and the distal end side. The burner has a premixed gas passage formed to surround the fuel passage. The burner has a fuel introduction part introducing the fuel channeled through the fuel passage into the premixed gas passage from the base end side to the distal end side. The burner has an air supply part supplying the premixed gas passage with air on the base end side.