A totally aerated combustion burner equipped with a combustion plate in which a multiplicity of flame holes are formed to perform totally aerated combustion by ejecting a premixed gas from the flame holes, the burner comprising, when such a side of the burner as is equipped with the combustion plate is defined as an upper surface, a width direction of the burner is defined as a lateral direction, and a depth direction of the burner is defined as a longitudinal direction: a distribution chamber facing a lower surface of the combustion plate; a mixing chamber on a lower side of the distribution chamber; an air supply on a lower side of the mixing chamber to thereby supply primary air from a combustion fan, wherein the mixing chamber has a front surface with a plurality of nozzle holes disposed in parallel with, and at a lateral distance from, one another so that a fuel gas to be ejected from the nozzle holes and the primary air from the air supply chamber get mixed in the mixing chamber to thereby generate the premixed gas for introduction thereof to the combustion plate through the distribution chamber; a wall plate disposed upright on a bottom surface of the mixing chamber in a manner to lie opposite to the front surface of the mixing chamber while leaving a ventilation clearance to the front surface so that the fuel gas ejected from each of the nozzle holes collides with the wall plate; an air inlet formed in such a portion at the bottom surface of the mixing chamber as to face the ventilation clearance, the air inlet being for introducing the primary air from the air supply chamber into the mixing chamber; and characterized by gutter-shaped baffle pates each being disposed in the ventilation clearance so as to be longitudinally elongated under the respective nozzle holes, wherein rising plate portions on respective lateral sides of each baffle plate are laterally inclined so that the upper-side distance of the rising plate portions becomes larger. a distribution chamber facing a lower surface of the combustion plate; a mixing chamber on a lower side of the distribution chamber; an air supply on a lower side of the mixing chamber to thereby supply primary air from a combustion fan, wherein the mixing chamber has a front surface with a plurality of nozzle holes disposed in parallel with, and at a lateral distance from, one another so that a fuel gas to be ejected from the nozzle holes and the primary air from the air supply chamber get mixed in the mixing chamber to thereby generate the premixed gas for introduction thereof to the combustion plate through the distribution chamber; a wall plate disposed upright on a bottom surface of the mixing chamber in a manner to lie opposite to the front surface of the mixing chamber while leaving a ventilation clearance to the front surface so that the fuel gas ejected from each of the nozzle holes collides with the wall plate; an air inlet formed in such a portion at the bottom surface of the mixing chamber as to face the ventilation clearance, the air inlet being for introducing the primary air from the air supply chamber into the mixing chamber; and characterized by gutter-shaped baffle pates each being disposed in the ventilation clearance so as to be longitudinally elongated under the respective nozzle holes, wherein rising plate portions on respective lateral sides of each baffle plate are laterally inclined so that the upper-side distance of the rising plate portions becomes larger.