A burner has: a combustion plate part for ejecting air-fuel mixture; and a flame rod which lies opposite to a portion of the combustion plate part which has a picture-frame-like burner frame; a metal-fiber knit which covers an opening enclosed by the burner frame; and a distribution plate which has formed therein distribution holes and which sandwiches the metal-fiber knit between the burner frame and the distribution plate through the distribution holes and the metal-fiber knit. The flame rod has: a rod base part which lies opposite to a portion of opening peripheral part of the burner frame which is positioned on the same surface level as the opening; and a rod main body part which lies opposite to a portion of the metal-fiber knit. The distance between the rod base part and the opening peripheral part is made smaller than the distance between the rod main body part and the metal-fiber knit.