PURPOSE: To effectively treat waste gas with a small quantity of powdery adsorbent by bringing the adsorbent a little contaminated and the regenerated adsorbent into contact with a gas to be treated of high concentration in the 1st stage and a gas to be treated of low concentration in the 2nd stage, respectively in a pneumatic carrying process.

CONSTITUTION: The waste gas treating apparatus is equipped with a regenerating device consisting of an adsorptive pneumatic carrying means 1, a separation means 2, a low temperature heating treatment means 3 and a high temperature heating treatment means 4, the 2nd stage adsorbent feed means 5, the 1st treatment means 6 and the 2nd treatment means 7. When the gas to be treated 8 is in a state of high component concentration of several hundreds ppm, the contaminated adsorbent separated by a cyclone 14A and the 1st bag filter 15A or by the 1st bag filter 15A only is returned to perform the primary adsorption. And when the gas to be treated is in a state of low component concentration of several tens ppm, it comes into contact with clean regenerated adsorbents to perform the secondary adsorption.