Abstract: A cleaning apparatus has a processing tank (21) for containing a processing liquid in which semiconductor wafers (W) are immersed, and a tubular vessel(22a) having a processing chamber (23) containing the processing tank (21). A side wall (26) of the vessel (22a), and a first partition wall (28) having an upright wall (27) standing on a bottom plate (23a) defining the bottom of the processing chamber (23) form a side ventilating duct (24). The bottom wall (30) of the vessel (22a), and a second partition wall (29) substantially horizontally extending from the lower end of the first partition wall (28) form a bottom ventilating duct (25). The side ventilating duct (24) and the bottom ventilating duct (25) can compactly arrange devices and pipes for supplying and discharging the cleaning liquid for cleaning semiconductor wafers (W), easily maintain the devices and pipes, easily arrange a ventilating system to the cleaning apparatus, and improve ventilation efficiency.