PURPOSE: To enable the rapid heating of a metal strip without causing damage to the metal strip by arranging induction heating devices and float-up nozzles along a carrying path of the metal strip formed in the horizontal direction.

CONSTITUTION: Plural induction heating devices 4 (4a, 4b, 4c) and plural pieces of float-up nozzles 5 (5a, 5b, 5c) are arranged along the carrying path 1 of a metal strip 3 formed in the horizontal direction. The coated metal strip 3 is carried along the carrying path 1 toward the arrow mark 2 direction and heated by supplying the electric power to the induction heating devices 4 and floated up by blowing the suitable temp. of gas from the float-up nozzles 5. By this method, the metal strip 3 is carried in the extremely light condition having no flaw and little tension and can efficiently be heated.