This disclosure relates to an oral cavity washing device including: a device body including a pump configured to discharge washing liquid, and a body unit including a tank provided at the device body； a tube connected to the body unit and configured to allow the discharged washing liquid to flow through the tube； and a washing unit connected to the tube and configured to discharge the washing liquid. The body unit has a two-dimensional shape like an ellipse or an approximate ellipse in a planar view.
