A dishwasher comprising: a tub ; a spray arm configured to spray washing water into the tub ; a steam supply unit configured to discharge steam into the tub ; a sump configured to store washing water; and a pump that is configured to supply washing water stored in the sump to the spray arm , that is configured to generate steam, and that is configured to supply steam to the steam supply unit , wherein the pump comprises: a housing ; a washing water inlet pipe coupled to the housing to receive washing water; a washing water outlet pipe coupled to the housing to discharge the washing water; an impeller disposed in the housing to transfer the washing water from the washing water inlet pipe to the washing water outlet pipe ; a heater coupled to the housing to heat the washing water in the housing and generate steam; and characterized by : a steam discharge pipe coupled to the washing water outlet pipe to discharge the steam generated by the heater , and wherein the pump comprises a partition wall dividing the inside of the housing into an upper portion and a lower portion, and having a communication hole communicating the upper portion and the lower portion thereof at one side thereof, wherein the impeller is disposed in the upper portion of the housing . a tub ; a spray arm configured to spray washing water into the tub ; a steam supply unit configured to discharge steam into the tub ; a sump configured to store washing water; and a pump that is configured to supply washing water stored in the sump to the spray arm , that is configured to generate steam, and that is configured to supply steam to the steam supply unit , wherein the pump comprises: a housing ; a washing water inlet pipe coupled to the housing to receive washing water; a washing water outlet pipe coupled to the housing to discharge the washing water; an impeller disposed in the housing to transfer the washing water from the washing water inlet pipe to the washing water outlet pipe ; a heater coupled to the housing to heat the washing water in the housing and generate steam; and characterized by : a steam discharge pipe coupled to the washing water outlet pipe to discharge the steam generated by the heater , and wherein the pump comprises a partition wall dividing the inside of the housing into an upper portion and a lower portion, and having a communication hole communicating the upper portion and the lower portion thereof at one side thereof, wherein the impeller is disposed in the upper portion of the housing . a housing ; a washing water inlet pipe coupled to the housing to receive washing water; a washing water outlet pipe coupled to the housing to discharge the washing water; an impeller disposed in the housing to transfer the washing water from the washing water inlet pipe to the washing water outlet pipe ; a heater coupled to the housing to heat the washing water in the housing and generate steam; and characterized by : a steam discharge pipe coupled to the washing water outlet pipe to discharge the steam generated by the heater , and wherein the pump comprises a partition wall dividing the inside of the housing into an upper portion and a lower portion, and having a communication hole communicating the upper portion and the lower portion thereof at one side thereof, wherein the impeller is disposed in the upper portion of the housing . a steam discharge pipe coupled to the washing water outlet pipe to discharge the steam generated by the heater , and wherein the pump comprises a partition wall dividing the inside of the housing into an upper portion and a lower portion, and having a communication hole communicating the upper portion and the lower portion thereof at one side thereof, wherein the impeller is disposed in the upper portion of the housing . <EOS>