In silico research, which reproduces living organisms with a numerical model, is not limited to conventional research that focuses on the elucidation of biological functions, but is currently expanding dramatically and expanding its field of activity. FDA has formulated the guidance on the use of in silico for medical device development, and the environment for medical device development and evaluation using in silico is rapidly being established. In Japan as well, its importance is increasing, as the next-generation medical device guidelines include a description of medical device evaluation using in silico. We will introduce the latest trends in in silico and medical device development / evaluation, which are leading overseas, with specific examples of devices that actually utilize in silico.