Provided is a device for assisting in the operation of returning the tilt angle of a torso to a reference direction. A balancing device is provided with a sensor, at least one flywheel, and a controller. The sensor detects the tilt angle of the torso with respect to the reference direction. The at least one flywheel is provided to the balancing device so that the axis line is not parallel to the yaw axis of the torso when attached to a person. The yaw axis of the torso corresponds to the longitudinal direction of the torso. Further, the yaw axis coincides with the reference direction when a person stands upright. The controller changes the rotation speed of the flywheel on the basis of the tilt angle detected by the sensor.