Position angle analysis by learning algorithm on robotics is extremely important as a tool for predictive maintenance to detect faults and mechanical problems. This paper presents position angle analysis on passive joint using three rotations (3R) underactuated robot manipulator. Experiment was conducted to predict the position angle which were applied to three joint; Active 1, Active 2 and Passive respectively. Experiment by SIMULINK software was carried out to validate the value of position angle obtained during real-time experiment. As a conclusion, the 3rd position angle of passive joint followed the position angle for Active 1 and Active 2.