A charging system for an autonomous underwater vehicle includes: a sea floating body; a charging station suspended in water from the body through a string-shaped body and located downstream of the sea floating body by receiving a water flow, the station including a noncontact electricity supplying portion located away from the string-shaped body; and an autonomous underwater vehicle coupled to the station that is rotatable about the string-shaped body, the vehicle including a noncontact electricity receiving portion configured to receive electricity supplied from the supplying portion, wherein: the station takes by the water flow such a posture that the noncontact electricity supplying portion is located downstream of the string-shaped body in a water flow direction; and when the vehicle is coupled to the station, the vehicle takes by the water flow such a posture that the receiving portion is located downstream of the string-shaped body in the water flow direction.