To provide a combustion chamber for preventing sulfuric acid corrosion (low-temperature corrosion) due to acid dew formation and at the same time preventing oxidation corrosion (high-temperature oxidation) due to high- temperature oxidation and the thermal damage of a refractory.

In a combustion chamber (10) having a body (14) comprising a cylindrical skin steel plate (11), and a fireproof brick (12) and a heat-insulating brick (13) that are subjected to inner lining to the inner surface of the skin steel plate (11), a porous plate (15) for thermal insulation is provided at the outer periphery of the skin steel plate (11), and a space (16) is included between the skin steel plate (11) and the porous plate (15).