To remarkably lower air humidity and effectively eliminate harmful matter and aromatic matter by containing an effective adsorbent on harmful matter in a filter, and connecting this filer to the post stage of a sorption reaction container for absorbing the humidity of air.

An air flow treatment device 1 is formed by accommodating a sorption reaction container 3 and an activated carbon filter 4 in an air guide housing 2. The sorption reaction container 3 and activated carbon filter 4 are formed as hollow frustrums of cone and mutually inserted so as to be brought into contact with each other in large area. An air guide passage 7 with a heating device 8 inside is provided on the large diameter part side, and a blower 6 is disposed in front of the air guide passage 7. A closing wall 18 is disposed at the end part on the small diameter part side, and a hollow chamber 9 in the sorption reaction container 3 is separated from an air chamber 5 by the closing wall 18. Air passages 12, 14 selectively opened/closed by a flag 15 are opened to the air chamber 5.