This paper focuses on the vibration analysis of planar cable?driven parallel robots on their configurations. Despite of many advantages of the cable robots, elasticity of the cables may cause the vibration at the existence of external disturbance, resulting in deterioration of positioning accuracy. According to the vibration theory, having high first order natural frequency can prevent resonance with low frequency disturbance from the surrounding environment. A series of simulations showed that choosing frame / end-effector shape and cable connection method affects robots’ natural frequency. For the precise simulation, the cables are modeled as linear springs and axial vibration of cables is mainly considered. Aspect ratios of the frame and end-effector are defined as non-dimensional parameters while their areas are fixed. It was shown that vibration analysis guides to design a planar cable robot in terms of high capacity to reduce vibration.