PURPOSE: To simplify a supporting structure for a boiler without a need of a suspension bar by placing a pipe holder at an upper end of a heat transfer pipe on a horizontal supporting beam.

CONSTITUTION: A supporting metal 8 is mounted on a horizontal pipe holder which is connected with upper ends of a plurality of substantially vertical heat transfer wall pipes 4, and placed directly on a horizontal supporting beam 3. Load of a boiler 1 is transferred to the pipe holder 5 through the heat transfer wall pipes 4, and the trasferred load is supported directly by the supporting beam 3 which passes below the supporting metal 8 mounted on the horizontal pipe holder 5. The supporting beam 3 is jointed to iron supportds arranged around the boiler 1, through which the load of the boiler 1 is finally transferred to the earth. By this, a suspension bar, which has been needed in a conventional structure, can be eliminated. In addition, a boiler supporting structure can be simplified and a height of the iron support can be lowered. Thus cost can also be reduced.