A modularization approach for gravity compensation of planar articulated robotic manipulators is addressed in this chapter. The modularization is realized by installing a set of gear-spring modules (GSMs) on the manipulator so that the gravitational torques can be eliminated by the spring torques applied on its joints. The design concept and mathematical formulation for the gravity compensation of the GSM are presented. Then, the gravity compensation of the manipulator by using the GSMs is proposed. Evaluation criteria for the performance of the design are suggested. Last, selected examples of planar-type serial and quasi-serial manipulators are provided for illustrating the design concepts and their performances.