This paper deals with mechanical and hardware design of a robot, used for the rehabilitation of upper extremities. It has been called ARR-1 (Arm Rehabilitation Robot). The robot has a semi-exoskeleton structure. This means that some parts of the robot fit closely to the human arm (an orthosis), but the weight of the construction does not load patient’s body. The device is used for the whole arm rehabilitation, but active joints are only situated in glenohumeral and elbow joints. The robot is electrically actuated.