Abstract: A prosthetic wrist unit providing a connection between the arm and a hand mechanism, comprising a wrist base unit with at least one connection slot into which the hand mechanism is to be inserted and at least one connecting piece enabling the rotational movement of the prosthetic wrist unit; a joint including a joint seat and a joint body; a locking mechanism comprising a locking mechanism opening into which the joint body is inserted and enabling the prosthetic wrist unit to operate in two positions, i.e., fixed or movable; an arm coupling unit into which the joint and the locking mechanism are inserted and which restricts the movement of the joint and the locking mechanism; and at least one tendon ensuring the joint stiffness of the prosthetic wrist unit.