This project proposes the design of a 4 DOF exoskeleton robotic arm for rehabilitation. This proposed robot arm can be used easily with either the user’s left or right arm. This robot arm is designed to have low inertia, high stiffness link, and zero backlash transmissions. It supports the patient’s arm during rehabilitation which is a repetitive task and takes a period of time. Each joint of this exoskeleton can be rotated from -90 to 90 degrees. From the result of joint trajectory of exoskeleton, this exoskeleton can support the daily movement of human arm and can be utilized for both arms. Furthermore, this proposed robot arm can be applied as a therapeutic and diagnostics device for physiotherapy, assistive device for human power amplifications.