Abstract: A fluid power generation device is configured to provide electric power generation using fluid action, and comprises multiple power generation mechanisms. Each power generation mechanism comprises: a casing that allows a fluid to pass through its internal space; and a power generation unit arranged within the casing, and configured to perform electric power generation using the fluid action. The casing is configured to generate vortexes in the vicinity of its fluid outlet. The multiple casings are arranged with spaces as intervals between them. Each casing generates vortexes in the vicinity of its fluid outlet. Furthermore, such an arrangement provides an interaction effect between the vortexes generated in the vicinity of the fluid outlets of the multipole casings arranged with the spaces as intervals between them. This provides a synergistic effect for accelerating the inner flow based on the interaction between the power generation mechanisms.