A grate bar comprising: an upper wall portion which extends in a first direction (D); a front wall portion which extends downward from a distal end of the upper wall portion ; a channel (S) which is formed on a back side of the upper wall portion ; and a partition wall which vertically divides the channel (S) and includes a partition wall main body of which a main surface faces the upper wall portion and a plurality of cooling holes which are formed in the partition wall main body and which are configured to eject a cooling medium (C) toward a back surface of the upper wall portion to cool the upper wall portion by impingement-cooling, characterized in that the grate bar comprises a pair of side wall portions which extends downward from a side edge of the upper wall portion ; and a rear wall portion which has a plate shape protruding downward from the upper wall portion and formed so that a main surface of the rear wall portion faces the first direction (D), wherein the upper wall portion , the front wall portion , the pair of side wall portions , and the rear wall portion are formed integrally, wherein the partition wall main body is connected to the front wall portion , the pair of side wall portions , and the rear wall portion , wherein the partition wall main body divides the channel (S) into an upper channel (S1) between the upper wall portion and the partition wall main body and a lower channel (S2) below the partition wall main body , wherein the partition wall main body includes a main portion which is parallel to the upper wall portion , and a distal end portion which is connected to a distal end side of the main portion , and wherein at least one of the plurality of cooling holes formed in the distal end portion is directed so that the cooling medium (C) ejected from at least one of the plurality of cooling holes is configured to hit the front wall portion in the upper channel (S1). an upper wall portion which extends in a first direction (D); a front wall portion which extends downward from a distal end of the upper wall portion ; a channel (S) which is formed on a back side of the upper wall portion ; and a partition wall which vertically divides the channel (S) and includes a partition wall main body of which a main surface faces the upper wall portion and a plurality of cooling holes which are formed in the partition wall main body and which are configured to eject a cooling medium (C) toward a back surface of the upper wall portion to cool the upper wall portion by impingement-cooling, characterized in that the grate bar comprises a pair of side wall portions which extends downward from a side edge of the upper wall portion ; and a rear wall portion which has a plate shape protruding downward from the upper wall portion and formed so that a main surface of the rear wall portion faces the first direction (D), wherein the upper wall portion , the front wall portion , the pair of side wall portions , and the rear wall portion are formed integrally, wherein the partition wall main body is connected to the front wall portion , the pair of side wall portions , and the rear wall portion , wherein the partition wall main body divides the channel (S) into an upper channel (S1) between the upper wall portion and the partition wall main body and a lower channel (S2) below the partition wall main body , wherein the partition wall main body includes a main portion which is parallel to the upper wall portion , and a distal end portion which is connected to a distal end side of the main portion , and a main portion which is parallel to the upper wall portion , and a distal end portion which is connected to a distal end side of the main portion , and wherein at least one of the plurality of cooling holes formed in the distal end portion is directed so that the cooling medium (C) ejected from at least one of the plurality of cooling holes is configured to hit the front wall portion in the upper channel (S1). <EOS>