A moving plate (14) is movable in a fitting space (28) of a receptacle (25) between a protecting position and a retracted position. A sealing member (16) is closer to an opening than the moving plate (14) and closely contacts the inner surface of the receptacle (25). The moving plate (14) has arms (64) including inward projecting locking projections (66). A female housing (102) fits into the fitting space (28) of the receptacle (25) and includes a sealing surface (116) and recesses (112) on an outer surface. The sealing surface (116) contacts the inner surface of the sealing member (16) during connection to a male connector (10). The recesses (112) are recessed on a more forward side than the sealing surface (116) in a fitting direction into the fitting space (28), and locking projections (66) are locked to side surfaces of the recesses during separation from the male connector.