A method for reducing the dew point of a furnace atmosphere gas in a continuous annealing furnace for annealing a metal strip in a reducing atmosphere by passing the metal strip through a heating zone and a cooling zone in this order or through a heating zone, a soaking zone, and a cooling zone in this order, comprising: a step (a) for providing a circulator that includes a heat exchanger for heat exchange between a low-temperature gas and a high-temperature gas, a gas cooler for cooling a gas, and a dryer for dehumidifying a gas to a dew point of -45°C or less; a step (b) for sucking part of the atmosphere gas from the heating zone and/or the soaking zone; then a step (c) for passing the sucked part of the atmosphere gas through a high-temperature gas passage of the heat exchanger and decreasing the temperature of the sucked part of the atmosphere gas by heat exchange with a gas in a low-temperature gas passage; then a step (d) for passing the part of the atmosphere gas having a decreased temperature through the gas cooler to further cool the part of the atmosphere gas; then a step (e) for dehumidifying the further cooled part of the atmosphere gas to a dew point of -45°C or less in the dryer; then a step (f) for passing the dehumidified part of the atmosphere gas through the low-temperature gas passage of the heat exchanger to increase the temperature of the dehumidified part of the atmosphere gas by heat exchange with a gas in the high-temperature gas passage; then a step (g) for returning the part of the atmosphere gas having an increased temperature to the heating zone and/or the soaking zone; and simultaneously with the step (f) and the step (g), a step (h) for returning part of gas flowing from the dryer toward the low-temperature gas passage of the heat exchanger directly to the cooling zone without passing through the heat exchanger. a step (a) for providing a circulator that includes a heat exchanger for heat exchange between a low-temperature gas and a high-temperature gas, a gas cooler for cooling a gas, and a dryer for dehumidifying a gas to a dew point of -45°C or less; a step (b) for sucking part of the atmosphere gas from the heating zone and/or the soaking zone; then a step (c) for passing the sucked part of the atmosphere gas through a high-temperature gas passage of the heat exchanger and decreasing the temperature of the sucked part of the atmosphere gas by heat exchange with a gas in a low-temperature gas passage; then a step (d) for passing the part of the atmosphere gas having a decreased temperature through the gas cooler to further cool the part of the atmosphere gas; then a step (e) for dehumidifying the further cooled part of the atmosphere gas to a dew point of -45°C or less in the dryer; then a step (f) for passing the dehumidified part of the atmosphere gas through the low-temperature gas passage of the heat exchanger to increase the temperature of the dehumidified part of the atmosphere gas by heat exchange with a gas in the high-temperature gas passage; then a step (g) for returning the part of the atmosphere gas having an increased temperature to the heating zone and/or the soaking zone; and simultaneously with the step (f) and the step (g), a step (h) for returning part of gas flowing from the dryer toward the low-temperature gas passage of the heat exchanger directly to the cooling zone without passing through the heat exchanger.