PURPOSE: To enable stable support of a heat transfer pipe group of a supercharger and an economizer, without the occurrence of buckling of a division water-cooled wall, by a method wherein the division water-cooled wall is hung down through a support member situated to the upper part of the division water-cooled wall for supporting heat transfer pipes.

CONSTITUTION: A boiler is formed with a furnace 1 and a cage part 2, and a supercharger 3 and an economizer 4 is contained in a cage part 2. A heat transfer pipe group of a supercharger 3 and an economizer 4 is supported to a support part disposed to a division water-cooled wall 5 and a cage part rear wall pipe 6. The division water- cooled wall 5 is hung down through a spring rod 8 and a support beam 7, both serving as a support member. A support beam 8 is supported by a side wall water-cooled wall 12 reinforced by a back stay 10, and a side wall water-cooled wall 12 is supported by a support 9. A load, e.g., the supercharger 3, the economizer 4, is supported by the division water-cooled wall 5. The load of the division water-cooled wall 5 is supported by the support beam 7 through the spring rod 8, and the load of the support beam 7 is supported by the side wall water-cooled wall 12 and the support 9. This constitution enables support of a heat transfer pipe group without reinforcing the division water-cooled wall 5 itself, and prevents the occurrence of buckling of pipes.