PROBLEM TO BE SOLVED: To provide a water flow generating device which does not require supply of driving energy such as electric power and the like from outside, and which is hardly affected by change of weather.SOLUTION: A water flow generating device includes: a heating side sealed container 4 and a cooling side sealed container 5 in which a high-pressure liquefied gas in a gas-liquid mixed state is filled； an evaporator 6 connected to the sealed container 4； a condenser 7 connected to the sealed container 5； reciprocating drive means 9 communicating with the sealed container 4 and connected to the sealed container 4 via flow passage change means 8； gas phase flow passages 13, 21, 23 for connecting the reciprocating drive means 9 and the condenser 7 via the flow passage change means 8； liquid phase flow passages 14, 16 for connecting the sealed container 5 and the evaporator 6； a drive shaft 19 for reciprocating being interlocked with the reciprocating movement of the reciprocating drive means 9； and water flow generation fins 31, 32, 33 accommodated under water and pivotally supported by the drive shaft 19 in a freely tiltable manner. The evaporator 6, the flow passage change means 8 and the reciprocating drive means 9 are heated at the same temperature as the sealed container 4.【課題】 外部からの電力等の駆動エネルギーの供給を必要とせず、しかも、天候の変化の影響を受けにくい水流発生装置を提供する。【解決手段】 気液混合状態の液化高圧ガスが充填された加熱側密封容器４及び冷却側密封容器５と、密封容器４に連結された蒸発器６と、密封容器５に連結された凝縮器７と、密封容器４と連通し、当該密封容器４に流路変更手段８を介して接続された往復駆動手段９と、流路変更手段８を介して往復駆動手段９と凝縮器７とを接続する気相流路１３、２１、２３と、密封容器５と蒸発器６とを接続する液相流路１３、１６と、往復駆動手段９の往復運動に連動して往復運動する駆動軸１９と、水中に収容され、駆動軸１９に傾動自在に軸支された水流発生フィン３１、３２、３３と、を備え、蒸発器６、流路変更手段８及び往復駆動手段９は、密封容器４と同等の温度で加熱される。【選択図】 図１
