A railcar damping device with an actuator (Af, Ar), wherein said device suppresses vibration of a vehicle body by controlling the actuator (Af, Ar), wherein the actuator comprises: a cylinder coupled to one of a truck and a vehicle body of a railcar; a piston inserted into the cylinder to be free to slide; a rod inserted into the cylinder and coupled to the piston and the other of the truck and the vehicle body; and a rod side chamber and a piston side chamber defined within the cylinder by the piston, wherein the railcar damping device comprises: a tank that is configured to store a liquid that is supplied to and discharged from the cylinder; a first opening/closing valve provided in a first passage connecting the rod side chamber to the piston side chamber to be capable of opening and closing the first passage; a second opening/closing valve provided in a second passage connecting the piston side chamber to the tank to be capable of opening and closing the second passage; a pump that is configured to be driven to rotate at a predetermined normal rotation speed in order to supply the liquid from the tank to the rod side chamber; characterised by the railcar damping device further comprising: a temperature determination unit that is configured to determine a temperature of the liquid supplied to the actuator, wherein a rotation speed of the pump is reduced below the normal rotation speed when the temperature determination unit determines that the temperature of the liquid is lower than a predetermined temperature, and the temperature determination unit is configured to determine whether or not the temperature of the liquid is lower than the predetermined temperature on the basis of date information. a cylinder coupled to one of a truck and a vehicle body of a railcar; a piston inserted into the cylinder to be free to slide; a rod inserted into the cylinder and coupled to the piston and the other of the truck and the vehicle body; and a rod side chamber and a piston side chamber defined within the cylinder by the piston, wherein the railcar damping device comprises: a tank that is configured to store a liquid that is supplied to and discharged from the cylinder; a first opening/closing valve provided in a first passage connecting the rod side chamber to the piston side chamber to be capable of opening and closing the first passage; a second opening/closing valve provided in a second passage connecting the piston side chamber to the tank to be capable of opening and closing the second passage; a pump that is configured to be driven to rotate at a predetermined normal rotation speed in order to supply the liquid from the tank to the rod side chamber; characterised by the railcar damping device further comprising: a temperature determination unit that is configured to determine a temperature of the liquid supplied to the actuator, wherein a rotation speed of the pump is reduced below the normal rotation speed when the temperature determination unit determines that the temperature of the liquid is lower than a predetermined temperature, and the temperature determination unit is configured to determine whether or not the temperature of the liquid is lower than the predetermined temperature on the basis of date information. a tank that is configured to store a liquid that is supplied to and discharged from the cylinder; a first opening/closing valve provided in a first passage connecting the rod side chamber to the piston side chamber to be capable of opening and closing the first passage; a second opening/closing valve provided in a second passage connecting the piston side chamber to the tank to be capable of opening and closing the second passage; a pump that is configured to be driven to rotate at a predetermined normal rotation speed in order to supply the liquid from the tank to the rod side chamber; characterised by the railcar damping device further comprising: a temperature determination unit that is configured to determine a temperature of the liquid supplied to the actuator, wherein a rotation speed of the pump is reduced below the normal rotation speed when the temperature determination unit determines that the temperature of the liquid is lower than a predetermined temperature, and the temperature determination unit is configured to determine whether or not the temperature of the liquid is lower than the predetermined temperature on the basis of date information. a temperature determination unit that is configured to determine a temperature of the liquid supplied to the actuator, wherein a rotation speed of the pump is reduced below the normal rotation speed when the temperature determination unit determines that the temperature of the liquid is lower than a predetermined temperature, and the temperature determination unit is configured to determine whether or not the temperature of the liquid is lower than the predetermined temperature on the basis of date information.