The method of cooling the cooling device and the steel plate of the steel plate

Cooling device of this steel sheet, a plurality of constraining roll pairs for restraining passage plate of steel; are arranged opposite to each other at a position between these constraining roll pairs in between the steel plate, the upper having a plurality of spray nozzle rows a cooling device and a lower cooling apparatus; includes a plurality of the plurality of spray nozzle rows are arranged along the sheet passing direction of the steel sheet, the respective spray nozzle rows, aligned in the width direction of the steel sheet same has a spray nozzle; when viewed along the through plate direction, the each spray nozzle rows, and the upstream spray nozzle row groups in the relatively upstream, in a relatively downstream are classified into a downstream spray nozzle row group; the number of said spray nozzles belonging to the upstream spray nozzle row group is less than the number of said spray nozzles belonging to the downstream spray nozzle row group.