Abstract: A method for calculating damping based on a fluid inertia effect is provided. Also, a fatigue test method and apparatus using the damping calculation method are provided. According to an embodiment, in a resonance fatigue test method for a test article, a processor of the apparatus calculates a damping ratio by considering an air inertia damping caused by a delayed response of air flow development among a fluid inertia effect on an oscillation of the test article. Then the processor constructs a damping model for predicting at least one of an amplitude of the test article and a test bending moment, based on the calculated damping ratio, and performs a resonance fatigue test based on the constructed damping model.