PROBLEM TO BE SOLVED: To provide a floating body having a vibration reducing function for efficiently suppressing vortex excitation vibration (VIM) of the floating body used by being floated on the ocean and the like, and a floating body having a vibration reducing function with a power generation system.SOLUTION: A floating body 100 comprises: a floating main body 10; an overhang structure 12 overhanging from the floating main body 10 to its surroundings structurally; and rotation means 14 attached to the overhang structure 12 through a shaft 20, and capable of rotating by the flow of fluid relative to the floating main body 10. The shaft 20 is connected to a power generator 16 mechanically, and transmits rotation force of the rotation means 14 to the power generator 16.
