The present invention controls rolling motion of a vehicle by eliminating the detrimental influence of gyro moment on the motion of the vehicle and actively using gyro moment generated by a flywheel constituting an energy storing device. The invention relates to an attitude control device for a vehicle mounted with a flywheel as an energy storage device, the flywheel being pivotally supported about first and second axes mutually orthogonal with each other, the flywheel being mounted on a body of the vehicle such that the first axis extends in a front-rear direction of the body, the attitude control device comprising locking means for locking movement of the flywheel about the first axis, wherein a rolling motion of the vehicle is controlled by locking the movement of the flywheel about the first axis using said locking means.