PURPOSE: To prevent the torque detection accuracy of a torque tension device from being dropped even when a capper is operated repeatedly and to maintain a cap- shutting (-opening) torque to be definite by a method wherein a planetary gear mechanism is used as the torque detection device.

CONSTITUTION: A cap-shutting torque is input to a control device in advance, a servometer is driven, a capping head is turned, and a cap is attached to the upper end of a container. That is to say, when the servomotor is driven by the control device, a sun gear 13 is turned to the clockwise direction by being interlocked with its driving shaft, individual planetary gears 14 are rotated to the counterclockwise direction, they are simultaneously revolved to the clockwise direction around the sun gear 13 and the capping head which is interlocked with it is turned to the clockwise direction. When the cap has been attached, a rotary force, in the counterclock direction, which acts on a protrusion 15a at an internal gear 15 is detected by a load cell 17, it is output to the control device, and the servomotor is controlled in such a way that a cap-shutting troque becomes a set value. Since a planetary gear mechanism is used instead of an elastic ring, the accuracy of the cap-shutting torque is not lowered even when the title device is operated repeatedly.