The high manufacturing a silicon steel strip having an excellent surface property with high reaction efficiency. From the vicinity of the location of each gas nozzle (1) with, forming a furnace length of the partition plate (2) parallel to the strip pass line in the direction, to face the partition plate end portion 20 of the furnace a longitudinal direction, along the strip by forming the dukche (3) stopping the gas flow, the strip and the partition plate 2 and the dukche 3 enclosed gap portion of chimgyu space formation, and (s) the partition plate end 20 and dukche 3 to (e _a), such as a, chimgyu space (s) after the from the gas in a furnace space of the outside to exhaust part for exhausting (e), and sprayed over the steel face from each of the gas nozzle (1), chimgyu space (s ) then the default configuration that the process gas flows within the to be exhausted from the exhaust section (e), the area of ​​the exhaust part (e) of the volume of the chimgyu space (s), chimgyu space (s) steel in the mass the optimization according to a particular condition.