To secure integrity of industrial product, various uncertainties surrounding the design technology must be treated properly. To do this, the uncertainties underlying during the following phases: evaluation of loads, modeling technique of systems of interest, evaluation of material strength, maintenance and inspection and so on, have to be clarified and effective measures to grasp the degree of the uncertainty and to reduce the inherent uncertainty have to be established.
The present paper shows the classification of the uncertainties and the fundamental relation with the design technology, and mentions a reliability design method based on probabilistic and statistical techniques, which has been getting popular in many engineering fields, and finally raises some future problems of design methods from the viewpoint of the uncertainties.