Abstract: A method of and apparatus for treating waste gas from semiconductor manufacturing equipment with a dry solid absorbent. A bypass pipe which is equipped with a bypass valve is provided between inlet and outlet pipes of a container packed with the absorbent, and when a reaction chamber of the semiconductor manufacturing equipment is evacuated to a level below that of atmospheric pressure, the bypass valve is opened to prevent the large amount of non-toxic gas that is discharged from the reaction chamber during the evacuation from being fed to the absorbent-packed container. Large variations in the flow rate of the gas are thus avoided and safe and efficient waste gas treatment with a dry solid absorbent having a relatively small particle diameter is possible.