A dual-purpose facility of continuous hot-dip coating and continuous annealing is configured so as to be switched between a continuous hot-dip coated material production line and a continuous annealed material production line, and includes a gas discharge path that discharges atmosphere gas in an annealing furnace from a gas discharge port provided in an outlet side of the annealing furnace out of the annealing furnace and a path opening and closing unit for opening and closing the gas discharge path. The path opening and closing unit opens the gas discharge path when the dual-purpose facility is used as the continuous hot-dip coated material production line and closes the gas discharge path when the dual-purpose facility is used as the continuous annealed material production line.