An oral cavity washing device (105) includes a housing (150), a tubular storage space formed in the housing (150) to store a liquid, and a pump (159) housed in the housing (150) to discharge the liquid. The housing (150) includes a peripheral wall section (172) constituting at least part of a peripheral wall of the storage space (170) and having a supply port (173) for supplying the liquid into the storage space (170), and a lid (171) disposed at one end of the storage space (170) to be able to entirely open and close a largest opening (178) that is larger in area than any other opening in the housing (150).
