A dishwasher includes: a tub which defines a space in which dishes are washed; a sump which accommodates washing water to be supplied into the tub; and a descaling solution supply device which supplies a descaling solution to the sump, in which the descaling solution supply device includes: a main flow path which guides washing water to be supplied to the sump; a solution accommodating unit which accommodates a descaling agent and has a solution outlet through which washing water, in which the descaling agent is dissolved, is discharged to the main flow path; a solution discharge valve which opens and closes the solution outlet; and a branch flow path which branches off from the main flow path, supplies the washing water into the solution accommodating unit, and has an atmosphere communicating port that communicates with the atmosphere.