To provide a jet preheating method and a preheating device which are easily adaptable to change in condition even when the change occurs, and enable improvement of production yield and stable operation by effectively utilizing waste heat from a radiant tube type heating furnace.

When performing the jet preheating of a strip 3 by the jet preheating device 2 disposed on the inlet side of the strip of the radiant tube type heating furnace 1, the temperature of the strip on the outlet side of the radiant tube type heating furnace 3 is controlled to be the target value by adjusting the preheating temperature by the jet preheating device 2.