To reduce necessary stock or cost, and increase convenience by solving problems in conventional methods with two kinds of devices, one with a control device incorporated in a manufacturing process, and the other not, that have required more stock in the stage of manufacturing, and higher burden of cost on customers, as well as special knowledge for simply mounting and removing it to worsen convenience.

In this device, the control device can be installed onto an opening/closing device to provide actuation performance, while it can also be used solely for controlling action of a cover on an opening part. Its structure comprises four component parts of a special gear, a movable piece, a torque case, and a frame. The special gear and the movable piece are provided with teeth up to a necessary rotation angle of the cover on the opening part. The special gear is rotated to the necessary rotation angle, and the movable piece moves only to an actuation part for the teeth. As the necessary rotation angle is reached, their teeth get into contact with a last teeth holding position after moving and dispersing torque in an angular direction so as to reduce torque. Since returning force is operating, move of the movable piece is stopped by slight force of the torque case, thereby the holding position can be maintained.