Recently, all kinds of industries, both in Japan and overseas, have been rapidly rolling out IoT (Internet of Things) systems. Although IoT offers advantages such as operational efficiency and business improvement through data analysis, one problem with IoT that is surfacing is the issue of security. As the number of cyberattacks on IoT systems has been increasing at overseas offices year after year, responding to such attacks using traditional perimeter control security model is becoming progressively more difficult. In response, the idea of zero trust, which assumes "not trusting anyone or anything" is now entering the spotlight. In this article, we will expound at length on the use of the zero trust security model in IoT at overseas offices.