To provide a method for removing water contained in a building material by which the contained water is discharged from the building material which has absorbed the water during construction work, and an air-dried state is restored.

In discharging the contained water from the building material used in an upper skeleton structure of a building during the construction work of a building, after the completion of the construction of the skeleton for constructing the upper skeleton structure on a foundation structure, an enforced ventilation device is installed in the upper skeleton structure and operated, and outside air is introduced to an inner space of the upper skeleton structure to promote the discharge of the contained water from the building material. After completing the discharge of the contained water, the enforced ventilation device is removed. A pressure ventilation device is preferably installed in an underfloor inspection port of a first floor so that the outside air introduced to the inner space of the upper skeleton structure is discharged to the outside via the inner space of the foundation structure.