In this paper, optimal kinematic design of planar manipulator with four-bar mechanism is presented. For the parallel manipulator, there is only one location defined between force and motion where local mobility index equals one. In this work, optimum link measurements of the manipulator that maximize the local mobility index depending on the input link location have been found and design charts for the optimum manipulator design have been obtained. As a result of this, it is shown that based on the determined link measurements, performance of the manipulator can be maximum not only for a certain position, but also for a position interval, as well. Additionally, better conditions have been obtained in terms of force-motion relationship compared to the parallel manipulator also at the positions where local mobility index is different than one. (C) 2004 Elsevier Ltd. All rights reserved.