Sway reduction device and float provided with same

Provided are a sway reduction device with which sway of a float body can be efficiently reduced by a simple structure, and a float provided with the sway reduction device. The sway reduction device is for a float body that floats on the water. The sway reduction device has: a plate part that is arranged to the lower side of the float body in the vertical direction, and that, viewed from the vertical direction, has a portion overlapping and a portion not overlapping the float body; and a connection part for connecting the plate part and the float body such that water can flow between the float body and the plate part. A flow channel through which the water flow over the bottom surface of the float body is faster in the direction going from the outside to the inside of the float body than in the direction going from the inside to the outside of the float body is formed with the bottom surface of the float body. 本发明提供种能够通过简单的结构有效地减少浮体主体的摇动的摇动减少装置及具备该摇动减少装置的浮体。本发明的摇动减少装置为漂浮在水上的浮体主体的摇动减少装置。所述摇动减少装置具有：板部，配置于浮体主体的垂直