NOVELTY - The apparatus has a gimbal that is rotated along a circumference of a gimbal axis. A flywheel is supported by gimbal. A second angular velocity acquisition unit acquires second angular velocity of circumference of second axis. The direction where first axis extended is different from direction orthogonal to a gimbal axis. The direction where second axis extended is orthogonal to gimbal axis. A control unit (13) changes gimbal axis along a direction orthogonal to first axis when a first angular velocity is larger than a second angular velocity.    USE - Gyro type electric power generating apparatus used in gyro system for obtaining motive power from rotation of gimbal using fluctuation energy e.g. wave to generator through power network (all claimed).    ADVANTAGE - The fluctuation of the gyro system along circumference of a gimbal axis is suppressed, so that antirolling of the gyro system of the circumference of the direction orthogonal to the gimbal axis is reduced. Thus, big motive power from a gimbal is obtained. The shake of a gyro system is suppressed during maintenance by keeping away a target natural period from the period of a wave. The big motive power from a gimbal is obtained by making a target natural period into the period of a wave. The attitude disorder in the water of a gyro system is suppressed, so that gyro system which dived into under the water surface is surfaced appropriately. Thus satisfied restart of operation is achieved when surfacing a gyro system again at sea.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a gyro system;    (2) an electric power generation method for obtaining motive power from rotation of gimbal using fluctuation energy; and    (3) a power network.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of the control structure of the gyro system. (Drawing includes non-English language text)    Control unit (13)    Angle detection sensor (14)    Gimbal angle sensor (15)    Gyro system angular velocity calculating unit (21)    Main command generation unit (22)