The most construction of conventional forceps robots developed for minimally invasive surgery are arm robots. Due to its configuration and motor alignment, arm robots are effected by large inertia force. These large inertia force make operators to drive robots difficulty. Therefore, in order to operate easily, the moving parts which are effected from gravity force should be small. Arm robots are made to imitate construction of the human. But since the motion is restricted by trocar in minimally invasive surgery, the arm construction may not be suitable. The one of the best way to move forceps is to drive trocar directly. In proposed mechanism, robots move trocar parts directly to make end effector small. Trocar has 3 degrees in one joint and tendon-drive system can realize multi degrees of freedom in one joint. Thus, tendon-drive is applied in proposed mechanism. Experiments show the validity of proposed method.