In this paper, we discuss the development of a robot finger capable of motion copying as part of the overall development of a robot hand capable of mimicking human movements. Motion copying requires the reproduction of both position and force, making it indispensable for accurate replication. The design of multi degree-of-freedom (DOF) fingers that take into account both position control and force control is discussed. It is desirable to achieve force control without the need for force sensors, as the inclusion of force sensors can impose limitations on bandwidth. In order to achieve force control without sensors, having backdrivability is an absolute requirement. The tendon-driven mechanism is a powerful means of transmitting power while maintaining backdrivability. This study is a highly significant research that enables the movement of all 4 DOF, including orthogonal joints, in a finger through the use of tendon-driven mechanisms across all joints. In this paper, a method enabling the movement of all four joints, including orthogonal joints, using tendon-driven mechanisms is presented, along with experiments demonstrating position control. The characteristics of the mechanism are used to derive the transformation matrices from motor-driven space to joint space. Control is then performed to independently move each joint.