Provided is an exhaust system of a wafer treatment device, and the main purpose thereof is to prevent secondary contamination of a wafer by not allowing foreign substances such as process gases and fumes and the like floating in the wafer treatment device to make contact with the wafer in a side storage. The wafer treatment device comprises: a cleaning device for removing foreign substances remaining on a wafer; and an exhaust device comprising first and second main bodies at the lower side of a main body of the wafer treatment device. By not allowing foreign substances such as process gases and fumes and the like floating in the wafer treatment device to make contact with a wafer in a side storage, secondary contamination of the wafer is prevented.