To generate and supply ideal saturated air having a desired dew-point temperature and humidity with high stability.

A saturated air generating device includes a saturation tank which is formed with a dual structure having a saturation tank body for accumulating water and a casing that surrounds the saturation tank body, and which defines a constant temperature solution jacket that accumulates a constant temperature solution for heating the water between the saturation tank body and the casing, a constant temperature solution tank which is provided to hold the saturation tank inside, which accumulates the constant temperature solution for heating the saturation tank, and which is formed to immerse entirety of the saturation tank in the constant temperature solution, a saturation tank temperature controlling section for setting a temperature of the constant temperature solution to be accumulated in the constant temperature solution jacket of the saturation tank at a desired temperature, and a constant temperature solution tank temperature controlling section for setting a temperature of the constant temperature solution to be accumulated in the constant temperature solution tank at a desired temperature.