Bending vibration characteristics of railway vehicles have been investigated in general under excitation tests, in which a carbody was directly excited by a shaker. It is however very difficult with their results to evaluate the ride quality of passengers under conditions that the vehicle runs on a certain track. The authors are therefore developing an evaluation system for vertical vibration of railway vehicles. This system consists of an excitation system equipped with linear actuators, the elastic supporting device installed between wheels and rails, and analytical techniques to estimate the power spectral density (PSD) and the ride quality level ( L _T) which feature the ride quality. In this paper, we describe the excitation tests performed using an actual commuter car and the estimated PSD and L _T are compared with what substantially measured under the running conditions.