A damping test method for executing a damping test for a hydraulically operated actuator used for driving a control surface of an aircraft, the method comprising the steps of: (a) acquiring an ideal velocity characteristic of the control surface that is defined by a temperature of pressure oil supplied to the actuator and an operating speed of the control surface; (b) acquiring, in a state where at least two of the actuators are attached to the control surface and a pair of oil chambers of the actuator among the actuators that is to be tested by the damping test are connected with each other via an orifice, a temperature of the pressure oil of the actuator to be tested and an operating speed of the control surface when the actuator(s) not under test actuate(s) the control surface; (c) correcting the ideal velocity characteristic of the control surface acquired in step (a) by using the temperature of the pressure oil of the actuator to be tested and the operating speed of the control surface acquired in step (b); (d) setting an upper limit and a lower limit for the operating speed of the control surface according to the temperature of the pressure oil by using a predicted value for a fluctuation range for a fluctuation factor previously assumed as a factor of fluctuation of the operating speed of the control surface, with reference to the ideal velocity characteristic corrected in step (c); (e) measuring, after execution of steps (a) to (d), a temperature of the pressure oil of the actuator to be tested and an operating speed of the control surface by actuating the control surface with the actuator not under test in a state where the pair of oil chambers of the actuator to be tested are connected with each other via the orifice; and (f) determining whether the operating speed measured in step (e) falls within a range between the upper limit and the lower limit set in step (d) at the temperature of the pressure oil measured in step(e). (a) acquiring an ideal velocity characteristic of the control surface that is defined by a temperature of pressure oil supplied to the actuator and an operating speed of the control surface; (b) acquiring, in a state where at least two of the actuators are attached to the control surface and a pair of oil chambers of the actuator among the actuators that is to be tested by the damping test are connected with each other via an orifice, a temperature of the pressure oil of the actuator to be tested and an operating speed of the control surface when the actuator(s) not under test actuate(s) the control surface; (c) correcting the ideal velocity characteristic of the control surface acquired in step (a) by using the temperature of the pressure oil of the actuator to be tested and the operating speed of the control surface acquired in step (b); (d) setting an upper limit and a lower limit for the operating speed of the control surface according to the temperature of the pressure oil by using a predicted value for a fluctuation range for a fluctuation factor previously assumed as a factor of fluctuation of the operating speed of the control surface, with reference to the ideal velocity characteristic corrected in step (c); (e) measuring, after execution of steps (a) to (d), a temperature of the pressure oil of the actuator to be tested and an operating speed of the control surface by actuating the control surface with the actuator not under test in a state where the pair of oil chambers of the actuator to be tested are connected with each other via the orifice; and (f) determining whether the operating speed measured in step (e) falls within a range between the upper limit and the lower limit set in step (d) at the temperature of the pressure oil measured in step(e).