PURPOSE: To efficiently perform drying treatment and material quality modifying treatment by covering one of the cut ends of a knotted bamboo material with a cover and sucking air in the cover to remove moisture from conductive tissue and covering the other cut end of the cover to inject a fluid in the cover.

CONSTITUTION: A cover 4 is attached to one cut end 2 of a round bamboo material 1 and one end of a pressure-resistant hose 7 is connected to the cover 4 and the other end of the hose 7 is connected to a vacuum pump 5. Moisture is sucked from the cut end 2 through the conductive tissue of the round bamboo material 1 by the vacuum pump 5. The cover 4 is also attached to the other cut end 3 of the round bamboo material 1 and a prescribed liquid is injected in the conductive tissue from the cover 4 by a pressure pump 6. Therefore, the drying of the bamboo material can be rapidly performed and the insect control and material quality modification due to the liquid can be performed at the same time.