PURPOSE: To discharge smoke out of a room through a smoke discharging device already installed and enable a flowing-down direction of collected oil droplets to be restricted at a local front end part by a method wherein a forced smoke discharging device is comprised of two parallel right and left suction ducts extending downwardly form a suction port, a central blowing-out duct, a blower assembled at a connected part between both ducts, and a filter inclined forwardly or rearwardly and rightwardly or leftwardly in respect to the suction ducts.

CONSTITUTION: As a blower 8 of a forced smoke discharging device 3 is operated and an already installed smoke discharging device 9 is operated, contaminated air generated is abruptly sucked from each of suction ports 11 opened at a front surface of a rear wall 15 into suction ducts 6, oil droplets or the like are collected and processed at a metallic filter 12 or a resin filter 13 until they are sucked into the blower 8, thereafter both speed and pressure are applied by the blower 8, they are blown into a blowing-out duct 7 and they are blown out from a blowing port 10 toward an already installed smoke discharging device 9 disposed above a heating and cooking table 2. Filters 12 and 13 are inclined to a forward direction and also inclined to right and left directions, so that the flowing-down direction of the oil droplets is restricted at a local front end part.