A detergent-supply system and a washing machine using the same. The detergent-supply system includes a guide rib formed on the bottom surface of a housing for guiding wash water, supplied to the rear part of the housing, to the front part of the housing, thereby washing out detergent remaining in the front part of the housing. The detergent-supply system further includes slits formed in the guide rib for spraying wash water, thereby completely eliminating the detergent remaining on the bottom surface of the housing.