Abstract: The study proposed a technique to analyse robot’s geometric error by using the data measured during circle contouring movement of the industrial robot end effectors. Each joints of the industrial robot must be set at a right angle to be able to move the robot’s end effectors to an intended position when an off line program is used. However, the robot joints do not form a precise right angle, the end effectors occurs position error when the robot is under operation. To analyze the angle error of the robot joints (i.e., datum location error), the position measured during circular contouring of the end effectors is used. The shape of the measured circle is also applied to analyze gear transmission error. The study carried out a simulation to find out that datum location error and gear transmission error are the important error factors for accuracy of articulated robots.