To improve the working efficiency of a heating work in which a casting can quickly be heated up and also, a core is broken with the movement of a fluidized bed and an oxidizing and reducing reaction of the heated air containing much oxygen and made to core sand and the core sand is supplied into the fluidized bed and thus, the heating treatment time is not needed to extend the necessary time for collapsing the core.

This is the heating method of the casting with the core to heated the casting with the core in the furnace with the fluidized bed.