PROBLEM TO BE SOLVED: To provide a device for suppressing rolling and pitching of floating body, which can suppress rolling and pitching of a floating body due to waves, and to provide a fish-preserve which can suppress rolling and pitching thereof due to waves.SOLUTION: A water column tube 10 attached to a floating body P installed by being floated on water surface, having a water side opening end 11 opening in water at one side, and having an atmosphere side opening end 12 opening in the atmosphere at another side, is provided. A natural period of vibration of a water column C in the water column tube 10 is about equivalent to a significant wave period of the water surface where the floating body P is installed. Energy of the waves is converted into vibrational energy of the water column C by vibrating the water column C in the water column tube 10 by the waves intruding from the water side opening end 11. Vibration of the water surface S of the water column C makes the atmosphere vibrate, and the vibrational energy of the water column C is converted into atmospheric vibrational energy. The energy of waves to act on the floating body P is absorbed and rolling and pitching of the floating body P by waves can be suppressed.
