A combustor comprising: a gas channel for oxygen-containing gas passing; a regulating member disposed in the gas channel, the regulating member partially shielding the gas channel, thereby introducing part of the oxygen-containing gas passing the gas channel into an inside area of the regulating member, while allowing passage of residue of the oxygen-containing gas toward a downstream side of a gas passing direction; a primary combustion zone formed in the inside area of the regulating member for combusting combustion fuel supplied from outside in conjunction with the part of the oxygen-containing gas introduced into the primary combustion zone; and a secondary combustion zone formed in the gas channel on a downstream side of the gas passing direction relative to the primary combustion zone, wherein in the secondary combustion zone, a porous ceramic body having heat resistance and gas permeability is disposed in the gas channel, an internal channel for introducing combustion exhaust gas generated in the primary combustion zone from an upstream side toward a downstream side of the gas passing direction is provided in the vicinity of a central portion of the porous ceramic body, and an external channel for introducing the residue of the oxygen-containing gas which has not been introduced into the primary combustion zone from an upstream side toward a downstream side of the gas passing direction is provided in the vicinity of an outer peripheral portion of the porous ceramic body, such that the residue of the oxygen-containing gas which has not been introduced into the primary combustion zone diffuses from the outside of the porous ceramic body into the porous ceramic body, wherein the porous ceramic body in the secondary combustion zone is disposed in the gas channel in such a manner as to contact the primary combustion zone on an upstream side of the gas passing direction relative to the porous ceramic body, and wherein the internal channel in the secondary combustion zone is a through hole formed in the vicinity of the central portion of the porous ceramic body. a gas channel for oxygen-containing gas passing; a regulating member disposed in the gas channel, the regulating member partially shielding the gas channel, thereby introducing part of the oxygen-containing gas passing the gas channel into an inside area of the regulating member, while allowing passage of residue of the oxygen-containing gas toward a downstream side of a gas passing direction; a primary combustion zone formed in the inside area of the regulating member for combusting combustion fuel supplied from outside in conjunction with the part of the oxygen-containing gas introduced into the primary combustion zone; and a secondary combustion zone formed in the gas channel on a downstream side of the gas passing direction relative to the primary combustion zone, wherein in the secondary combustion zone, a porous ceramic body having heat resistance and gas permeability is disposed in the gas channel, an internal channel for introducing combustion exhaust gas generated in the primary combustion zone from an upstream side toward a downstream side of the gas passing direction is provided in the vicinity of a central portion of the porous ceramic body, and an external channel for introducing the residue of the oxygen-containing gas which has not been introduced into the primary combustion zone from an upstream side toward a downstream side of the gas passing direction is provided in the vicinity of an outer peripheral portion of the porous ceramic body, such that the residue of the oxygen-containing gas which has not been introduced into the primary combustion zone diffuses from the outside of the porous ceramic body into the porous ceramic body, wherein the porous ceramic body in the secondary combustion zone is disposed in the gas channel in such a manner as to contact the primary combustion zone on an upstream side of the gas passing direction relative to the porous ceramic body, and wherein the internal channel in the secondary combustion zone is a through hole formed in the vicinity of the central portion of the porous ceramic body.