PURPOSE: To perform heating of a bath room without circulating air by convection, by locating a blower and a heater at the inside of an air duct joining together an exhaust port and a suction port provided at the outside of a bath room, and by heating a radiation plate by hot blast flowing through the air duct.

CONSTITUTION: A damper 6 is first closed, a blower 3 being driven after heating a heater 4. Hot blast flowing out of an exhaust port of an air duct 2 and passing through a space provided between a ceiling surface of a bath room 1 and a radiation plate 5 is returned to its initial position after being sucked from a suction port of the air duct 2. Heat is radiated into the bath room 1 as a result of the radiation plate 5 being heated by said hot blast, whereby the inside of the bath room 1 is heated. In the case of a damper 6 being opened, hot blast fed through an exhaust port of the air duct 2 passes through the damper 6 into the bath room 1 wherein it becomes a warm air. Said air being then sucked from a suction port of the air duct 2 is heated to become hot blast which is blown off again through the exhaust port of the air duct 2. Thus heating of the bath room can be performed without circulating air by convection, and this causes men taking a bath not to feel the cold.