A dishwasher comprising: a tub; a spray arm (3, 5) 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 (3, 5), 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 (3, 5) 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 (3, 5), 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.