A continuous casting machine is directly coupled to a rolling facility has many machines in a series including the rolling machine disposed downstream of the continuous casting machine. When one of the machines is stopped, the slab is still continuously produced by the continuous casting machine, but is sheared on the upstream side of the rolling machine and coiled in its hot state rather than rolled. Even though the rolling operation is interrupted, all of the slab being produced by the continuous casting machine is coiled so that the molten metal produced for the casting is not wasted. After the machine that has shut the line down is able to be restarted, the slab that has been stored in its hot state is uncoiled and supplied to the downstream machines.