The present disclosure relates to an oral cavity washing device including a body unit including a pump configured to discharge washing liquid, a tube connected to the body unit and configured to allow the discharged washing liquid to flow through the tube, a washing unit connected to the tube and configured to discharge the washing liquid, a joint portion configured to detachably attach the washing unit to the body unit, a disposing portion provided at the body unit and configured to allow the tube to be disposed at the disposing portion in a state where the washing unit is attached to the body unit, and an elastic member provided at the disposing portion.