A connector (10A) is provided with a housing (20) including a tube (22) and a seal (80) to be fit in the tube (22) in a liquid-tight manner. A holder (60) has a peripheral wall (62) fit externally on the tube (22) and a rear wall (61) configured to prevent the seal (80) from coming out backward. A wire cover (50) is mounted on the housing (20) by being fit externally on the peripheral wall (62) when the wire cover (50) is arranged to cover wires (100) pulled out from the holder (60) and the peripheral wall (62) is disposed in a proper posture on the tube (22). However, the wire cover (50) interferes with the holder (60) and cannot be mounted on the housing (20) when the peripheral wall (62) is in an improper posture inclined with respect to the tube (22).