A combustor comprising: a fuel nozzle for jetting out a hydrogen-containing fuel into a combustion chamber formed at a downstream side; an air hole plate of a flat-plate shape disposed between the fuel nozzle and the chamber, the air hole plate facing an upstream side of the chamber; a plurality of air holes provided in the air hole plate, in a circumferential direction relative to a central axis of the air hole plate, wherein the fuel nozzle is arranged to inject fuel centrally within each of the plurality of air holes, such that a fuel flow and an air flow formed at an outer circumferential side of the fuel flow are blown out into the chamber from the respective air holes; characterized in that the air holes are disposed in a plurality of rows on the air hole plate in a radial direction relative to the central axis of the air hole plate; wherein a clearance defined between any two circumferentially adjacent air hole inlets provided on a face of the air hole plate that is nearer to the fuel nozzle is formed wider than a clearance defined between any two circumferentially adjacent air hole outlets formed on a face of the air hole plate that is nearer to the chamber, wherein the air holes are inclined in the circumferential direction of the air hole plate so that the fuel flow and air flow blown out from the air holes each become a swirling flow that streams to a downstream side while swirling spirally inside the chamber, and the relationships of formulas 1 to 3 are satisfied N > 1 0.615 D 2 t + 0.594 a t 1 0.786 a t 5 − 2.46 a t 4 + 2.98 a t 3 − 1.79 a t 2 + 0.581 a t + 0.0115 N × a < 1 b < 1 0.105 a t 3 − 0.247 a t 2 + 0.226 a t + 0.00215 N × a θ < sin − 1 − 0.232 a t + 0.156 D 2 t N + 0.165 a t N with "N" being the number of air holes, wherein N is more than four, "t" being the thickness of the air hole plate, "D2" being a diameter of the air holes, "a" being the clearance between any two air hole outlets on the air hole plate face nearer to the chamber, "b" being the clearance between any two air hole inlets provided on the air hole plate face nearer to the fuel nozzle, and "θ" being the swirling angle imparted to the air holes, defined by an angle formed between a plane that includes the central axis of the air hole and a plane perpendicular face of the air hole plate. a fuel nozzle for jetting out a hydrogen-containing fuel into a combustion chamber formed at a downstream side; an air hole plate of a flat-plate shape disposed between the fuel nozzle and the chamber, the air hole plate facing an upstream side of the chamber; a plurality of air holes provided in the air hole plate, in a circumferential direction relative to a central axis of the air hole plate, wherein the fuel nozzle is arranged to inject fuel centrally within each of the plurality of air holes, such that a fuel flow and an air flow formed at an outer circumferential side of the fuel flow are blown out into the chamber from the respective air holes; characterized in that the air holes are disposed in a plurality of rows on the air hole plate in a radial direction relative to the central axis of the air hole plate; wherein a clearance defined between any two circumferentially adjacent air hole inlets provided on a face of the air hole plate that is nearer to the fuel nozzle is formed wider than a clearance defined between any two circumferentially adjacent air hole outlets formed on a face of the air hole plate that is nearer to the chamber, wherein the air holes are inclined in the circumferential direction of the air hole plate so that the fuel flow and air flow blown out from the air holes each become a swirling flow that streams to a downstream side while swirling spirally inside the chamber, and the relationships of formulas 1 to 3 are satisfied N > 1 0.615 D 2 t + 0.594 a t 1 0.786 a t 5 − 2.46 a t 4 + 2.98 a t 3 − 1.79 a t 2 + 0.581 a t + 0.0115 N × a < 1 b < 1 0.105 a t 3 − 0.247 a t 2 + 0.226 a t + 0.00215 N × a θ < sin − 1 − 0.232 a t + 0.156 D 2 t N + 0.165 a t N with "N" being the number of air holes, wherein N is more than four, "t" being the thickness of the air hole plate, "D2" being a diameter of the air holes, "a" being the clearance between any two air hole outlets on the air hole plate face nearer to the chamber, "b" being the clearance between any two air hole inlets provided on the air hole plate face nearer to the fuel nozzle, and "θ" being the swirling angle imparted to the air holes, defined by an angle formed between a plane that includes the central axis of the air hole and a plane perpendicular face of the air hole plate.