In this study, the possibility of application of fuzzy resaoning method was discussed on the problems of determining the inspection time appropriately to keep the fatigue reliability of ships or ocean structural members through the service. For ships or ocean structural members, the stress distribution and the fatigue properties of members usually have some uncertainties. Also the ability of inspection is apt to depend on human factors. Therefore it is difficult to determine the suitable time of repeating inspections before the service by probabilistic analysis. In the fuzzy reasoning method proposed here, the next inspection time ( I _k+1 ) after the completion of k -th inspection ( I _k ) is inferred based on the inspection results obtained by this time by the subjective judgements. The degree of fatigue damage detected by k -th inspection and the increasing or decreasing tendency of fatigue damage observed in the recent inspections were taken in to consideration in the inference. The next inspection interval Δ y _k+1 , which is expressed as a function of this inspection interval Δ y _k , is adjusted such that the fatigue relia bility between this and next inspection time would be maintained to a desirable level. Judge ment factors used in the inferences are the number, the average length and the maximum length of detected cracks. The capability of the fuzzy reasoning method was examined by the numerical simulation. With appropriate fuzzy conditional statements and the membership functions, it was concluded that the inspection time can be determined maintaining the fatigue reliability of the members through the service.