A marine wind power generation floating body according to an embodiment of the present disclosure can be coupled to a tower used for wind power generation and is provided at sea. The marine wind power generation floating body includes a floating main body which is formed at a predetermined length and which has a circular transverse cross section, a ballast part positioned on one side of the floating main body, a damping plate positioned at one end of the floating main body, and formed with a diameter that is larger than the outer diameter of one side of the floating main body, and a pitching/rolling damping part which is positioned on the other side of the floating main body, and which damps the horizontal pitching and rolling of the floating main body.