To decrease a temperature difference between upper and lower parts in a room during the use of an air-conditioner and to improve the energy efficiency of the air-conditioner.

A pipe 8 to suck up cold air near a floor is mounted on an air-conditioner 1 and the air is heated and supplied to eliminate cold air in a room. This constitution sucks cold air near a floor and reliably decreases the cold air. Sucked air is supplied to an air-conditioner 1 through the pipe 8. Since cold air flows through a heat-exchanger 2, heat-exchange efficiency is improved, and since heated air is successively supplied, warm air apt to gather in the vicinity of a ceiling is gradually forced downward and a whole of a room is warmed.