The present invention provides combustion catalysts that have high exhaust gas-purifying activity and are less expensive than conventional ones.The catalysts include: (1) A calcium salt, amorphous silica, and a copper compound, (2) Amorphous silica, and a copper compound, (3) (1) At least one of crystalline silica and amorphous silica, (2) a calcium salt, and (3) a copper oxide, and (4) (1) At least one of crystalline silica and amorphous silica, and (2) a copper oxide.