Prototypes of medical devices are made in accordance with the needs of clinical practice, and for systems required during the initial process of medical device development for new surgical practices. Verification of whether these prototypes produce the intended performance specifications is conducted using basic tests such as mechanical and animal tests. The prototypes are then improved and modified until satisfactory results are obtained. After a prototype passes through a clinical trial process similar to that for new drugs, application for approval is made. In the approval application process, medical devices are divided into new, improved, and generic types. Reviewers judge the validity of intended use, indications, operation procedures, and precautions, and in addition evaluate the balance between risk and benefit in terms of efficacy and safety. Other characteristics of medical devices are the need for the user to attain proficiency in usage techniques to ensure efficacy and safety, and the existence of a variety of medical devices for which assessment strategies differ, including differences in impact on the body in cases in which a physical burden to the body or failure of a medical device develops. Regulatory science of medical devices involves prediction, judgment, and evaluation of efficacy, safety, and quality, from which data result which can become indices in the development stages from design to application for approval. A reduction in the number of animals used for testing, improvement in efficiency, reduction of the necessity for clinical trials, etc. are expected through rational setting of evaluation items.