A vibration suppression device for a railway vehicle includes an actuator (5) disposed between a bogie truck (2) and a vehicle body (1), the actuator adjusting a vibration of the railway vehicle by extension/retraction motion thereof, and a controller (4) for controlling the extension/retraction motion of the actuator (5), and the controller (4) derives the total amount of extension/retraction displacements of the actuator (5) within a predetermined period of time during the running of the railway vehicle, and compares the derived total amount of extension/retraction displacements with a preliminarily registered threshold value to determine that the actuator (5) is seized in the case where the total amount of extension/retraction displacements is smaller than the threshold value. Thereby, seizing of the actuator can be self-diagnosed and found at an early stage.