Abstract: A caster to be mounted to a movable object, such as a hoop-shaped walking support for baby, a chair or the like and comprises a basic body turnably mounted at one end and provided at its opposite end with spaced apart axle supports for wheels, a stopper being mounted to the basic body and comprising a bearing portion received between the axle supports, a grounding surface adapted to contact the earth for stoppage of the caster the stopper including, an engaging part for setting the stopper above the lower margin of the wheels, a spring for urging the stopper downward, and a swing limiting projection for limiting the range of the swinging movement of the stopper.