To provide a method of predicting the damage due to the hydrogen embrittlement crack of a high-strength bolt or the like which is used when a structure such as a building, a bridge or the like by steel frames and reinforcing bars is built and to provide a method of deciding the time for executing effective measures against the damage of the bolt.

A dummy bolt whose quality is identical to that of the high- strength bolt or the like is coupled by a tightening force higher than that of the high-strength bolt, to a part near the coupling of the high-strength bolt or the like used when the structure such as the building, the bridge or the like by the steel frames and the reinforcing bars is built, the damage of the dummy bolt is detected, and the hydrogen embrittlement crack of the bolt is predicted. On the basis of the relationship between a load stress and the breakdown time in the hydrogen embrittlement crack, the breakdown time of the bolt is calculated, and the breakdown time of the bolt is predicted.