Omnidirectional vehicles have been widely applied in several areas, but most of them are designed for the case of motion on flat, smooth terrain, and are not feasible for outdoor usage. This paper presents an omnidirectional mobile robot that possesses highmobility in rough terrain. The omnidirectional robot employs four sets of mobility modules, called active split offset caster (ASOC). The ASOCmodule has two independently-driven wheels that produce arbitrary planar translational velocity, enabling the robot to achieve its omnidirectional mobility. Each module is connected to the main body of the robot via a parallel link with shock absorbers. In this paper, a design and development of the ASOC-driven omnidirectional mobile robot for rough terrain are described. Also, a control scheme that considers a kinematics of the omnidirectional mobile robot is presented. The omnidirectional mobility of the robot regardless of ifs heading direction is experimentally evaluated based on ametric called omnidirectional mobility index.