To provide a vibration tester for a railroad vehicle to perform vibration test in consideration of effects that the vibration characteristics of the railroad vehicle and the vibration characteristics of a rail have on each other.

This vibration tester for a railroad vehicle is equipped with a rail wheel 8 making contact with a wheel 5 of the railroad vehicle from below, a motor 6b for rotatively driving the rail wheel 8, a control means for controlling the rotation of the motor 6b, and a vibrating means 10 for displacing the rail wheel 8. This tester consists of a reactive force measurement means 14 interposed between the rail wheel 8 and the vibrating means 10 for measuring a load exerted on the rail by the railroad vehicle, and a vibration response calculation means 19 having a numerical model for a rail structure and calculating a vibration response of the numerical model at a time point after a definite period of time with the load measured by the measurement means 14 taken for external force to control the vibrating means 10 so as to reproduce rail displacement at a wheel ground-contacting position as to the numerical model.