PURPOSE: To efficiently obtain low-cost preheated air of a high temperature from exhaust gas of a high temperature by switching a high temperature resistant heat storage cell to exhaust gas and hot air passages by rotating a switching valve.

CONSTITUTION: A heat storage cell 3 is a ceramic heat storage material and normally a towerlike steel cylinder filled with crushed stones. A low temperature switching valve 5 switches in the cell 3 in synchronization with a high temperature switching valve 2. High temperature exhaust gas is introduced from a high temperature exhaust gas inlet 8, to the cell covered with the valve 2 of the cell 3 to preheat a heat storage layer of crushed stones and fed down. High temperature preheated air is communicated with the cell 3 not covered with the rotating valve 2, and effused from a low temperature exhaust gas outlet 10. The air is communicated with the cell 3 not covered with the valve 5, and introduced from an air inlet 11.