The present invention is to provide a sump assembly which enables leaked washing water therein to be circulated smoothly without remaining therein, and a dishwasher using the same cleanly and sanitarily. For this, the present invention includes a sump housing for holding washing water; an impeller housing secured to the sump housing for placing an impeller pumping the washing water therein; a filter housing provided on an upper portion of the impeller housing for placing a filter filtering the washing water therein; and a connection device for making a lower portion of the filter housing in communication with the sump housing. Owing to the above configuration, the dishwasher may be used cleanly and sanitarily, resulting in enhancing washing efficiency and endurance of a product.