To provide a continuous annealing furnace that can quickly reduce a dew point of a furnace atmosphere to a level suitable for stable operation and can stably obtain a low-dew-point atmosphere in which less problems are caused in terms of pickup defects and damage to a furnace wall, and to provide a steel strip continuous annealing method that utilizes the continuous annealing furnace.

This continuous annealing furnace is a vertical annealing furnace that is configured in such a manner that no partitioning wall is provided between a heating zone and a soaking zone, a portion of a furnace gas is sucked and introduced into a refiner, which is provided outside the furnace and has a deoxygenation device and a dehumidification device, in order to lower the dew point by removing oxygen and moisture, and the gas having the lowered dew point is returned into the furnace. Gas suction ports to the refiner are provided in the heating zone and/or the soaking zone, except in a lower part of a connection section between the soaking zone and a cooling zone and in an area that is located at a distance of 6 m or less from a steel strip introduction section which is provided at a bottom of the heating zone, in the vertical direction and that is located at a distance of 3 m or less in a length direction of the furnace. Gas discharge ports from the refiner into the furnace are provided in an area that is located higher than a path line of the connection section between the soaking zone and the cooling zone and in an area that is located higher than a position 2 m below a center of upper hearth rolls which are provided at a top of the heating zone, in the vertical direction.