A charging system for an autonomous underwater vehicle, the charging system comprising: a sea floating body floating on a sea; a charging station suspended in water from the sea floating body through a string-shaped body and located downstream of the sea floating body in a water flow direction by receiving a water flow, and an autonomous underwater vehicle coupled to the charging station so as to be rotatable about the string-shaped body, characterized in that the charging station includes a noncontact electricity supply portion located at a position away from the string-shaped body, the autonomous underwater vehicle includes a noncontact electricity receiving portion configured to receive electricity supplied from the noncontact electricity supplying portion, the charging station takes by the water flow such a posture that the noncontact electricity supplying portion is located downstream of the string-shaped body in the water flow direction; in a state where the autonomous underwater vehicle is coupled to the charging station, the autonomous underwater vehicle takes by the water flow such a posture that the noncontact electricity receiving portion is located downstream of the string-shaped body in the water flow direction, the charging station includes a captured portion fixed to the string-shaped body and a station main body coupled to the captured portion; and the autonomous underwater vehicle includes an underwater vehicle main body and a capturing mechanism provided at a front end portion of the underwater vehicle main body and configured to capture the captured portion so as to be rotatable about the string-shaped body relative to the captured portion. a sea floating body floating on a sea; a charging station suspended in water from the sea floating body through a string-shaped body and located downstream of the sea floating body in a water flow direction by receiving a water flow, and an autonomous underwater vehicle coupled to the charging station so as to be rotatable about the string-shaped body, characterized in that the charging station includes a noncontact electricity supply portion located at a position away from the string-shaped body, the autonomous underwater vehicle includes a noncontact electricity receiving portion configured to receive electricity supplied from the noncontact electricity supplying portion, the charging station takes by the water flow such a posture that the noncontact electricity supplying portion is located downstream of the string-shaped body in the water flow direction; in a state where the autonomous underwater vehicle is coupled to the charging station, the autonomous underwater vehicle takes by the water flow such a posture that the noncontact electricity receiving portion is located downstream of the string-shaped body in the water flow direction, the charging station includes a captured portion fixed to the string-shaped body and a station main body coupled to the captured portion; and a captured portion fixed to the string-shaped body and a station main body coupled to the captured portion; and the autonomous underwater vehicle includes an underwater vehicle main body and a capturing mechanism provided at a front end portion of the underwater vehicle main body and configured to capture the captured portion so as to be rotatable about the string-shaped body relative to the captured portion. an underwater vehicle main body and a capturing mechanism provided at a front end portion of the underwater vehicle main body and configured to capture the captured portion so as to be rotatable about the string-shaped body relative to the captured portion.