A steel strip continuous annealing device has a vertical annealing furnace 10 in which a heating zone 14, a soaking zone 16, and a cooling zone 18 are arranged in this order, and anneals a steel strip P passing through the zones 14, 16, and 18 in the order while being conveyed in the vertical direction in the vertical annealing furnace 10. The heating zone 14, the soaking zone 16, and the cooling zone 18 communicate through an atmosphere separation portion 36. One of a gas delivery port 38 and a gas discharge port 40 is positioned in an upper part and the other one of the gas delivery port 38 and the gas discharge port 40 is positioned in a lower part in each of the heating zone 14, the soaking zone 16, and the cooling zone 18.