To provide an exhaust supply system and an exhaust supply method that stably exhibit an exhaust purification performance.SOLUTION: A exhaust supply system 1 has: a second exhaust passage 12 for feeding exhaust to a cultivation facility 71; a bag filter 41, an oxidation catalyst 43 and a denitration catalyst 44 for purifying the exhaust flowing in the second exhaust passage 12; and a first flow rate control damper 46 for controlling a flow rate of the exhaust fed to the cultivation facility 71. The first flow rate control damper 46 is provided downstream from the denitration catalyst 44 in the second exhaust passage 12 in the flow direction of the exhaust.SELECTED DRAWING: Figure 1