PURPOSE: To provide a heat accumulating device in which a required period of time for a heat accumulation completion is short and a heat accumulation can be efficiently performed.

CONSTITUTION: A heat accumulation member 1, an air passage 2 within the heat accumulation member 1, a blower 3, a heater 4 and a heat exchanger 5 are connected by a duct in the same manner as that of the prior art and air 7 is circulated in them. The heat accumulating member 1 is arranged vertically and the air passage 2 is arranged such that air flows in a vertical direction. When heat is accumulated, the blower 3 is operated to cause the air 7 to be circulated. The air 7 is heated by a heater and the heat air 7 of high temperature flows in the air passage 2 within the heat accumulating member from an upper part to a lower part so as to store heat uniformly within the heat accumulating member 1.