In order to convert wind energy into electrical energy efficiently in accordance with the wind direction, a control device (10) for a floating body wind-powered electricity generation device (1) controls a pitch angle control unit (18) by means of a pitch angle command value calculated on the basis of signals detected from a second sensor (a), which detects the phase angle of a nacelle (13) and a tower (12), and a third sensor (b), which detect the yaw angle from a reference position of the tower (12), such that the signal detected by a first sensor (16), which detects the wind direction deviation with respect to the direction orthogonal to the rotation plane of a windmill blades (15), is an angle within a prescribed range from the direction orthogonal to the rotation plane of the windmill blades (15). In addition, the control device controls a yaw drive device (17) by means of a yaw drive command value calculated on the basis of the signals detected from the second sensor (a) and the third sensor (b).