A process and an apparatus for treating exhaust gases, comprising an aeration stirring tank (5) employing an aqueous alkaline liquid, and, as a posterior stage, a gas-liquid contact device (7) and/or a packed column (11). The apparatus can remove at the posterior stage harmful gases that the aeration stirring tank fails to remove, for example, water-soluble organic compounds such as ethanol, halogenated silicon compounds such as SiCl₄, and halogen gases such as F₂ and Cl₂. The process and apparatus are particularly suitable for purifying exhaust gases discharged from a semiconductor production device.