In a perforated coaxial jet burner implemented by a lot of air-fuel coaxial jets, a swirl plate (33) as an end face of the burner on the combustion chamber's side has a lot of air holes for supplying unburned premixed gas of fuel and air to the combustion chamber. Grooves (36) are formed downstream of the air holes of the swirl plate. Adhesion of flame to the swirl plate is inhibited by feeding part of the unburned premixed gas to the grooves. Further, the width of each remaining part (37) between adjacent grooves is set at several millimeters that is approximately equal to the flame quenching distance, by which adhesion of flame to the remaining parts is also prevented. With this configuration, both stable combustion and low NOx combustion can be achieved irrespective of the load condition.