Abstract: A warm air blow-out device for box-shaped stove is disclosed, which comprises a casing having a warm air flow-out path formed in an upper portion of the casing interior and air withdrawal openings formed in a bottom and a front wall lower portion of the casing and a cross flow fan extending horizontally in an upper portion of the casing interior and rotated by a motor. The opposite sides of the bottom of the casing are provided with respective legs, which include permanent magnets which can be held attracted to the top of the stove. Behind the legs, support members are provided to be in contact with the rear wall of the room heater casing for supporting the casing of the device.