In this study, a simple method is proposed to obtain the optimum design parameters of vibration absorbers consisting of several tuned mass damper units connected each other in parallel. The method is essentially the extension of the formulas proposed by Den Hartog for single degree-of-freedom tuned mass dampers to multiple tuned mass dampers. To demonstrate the effectiveness of the proposed method, an application to high-speed rail bridges are made. The bridge is modeled as a simple Euler-Bernoulli beam, and the train is modeled as a series of moving loads. The equations of motion are solved numerically by the Newmark method. The results of the study showed that multiple tuned mass dampers designed by the proposed method show good performance in reducing the resonance vibrations in high-speed rail bridges.