This paper describes the role of affective interface in order to foster trust between human and machine. The affective interface is the interface, which deals with emotion, and it can communicate not only explicit information but also implicit information by exchanging kansei signals with humans. On the other hand, the trust is basically formed by the past experience or information, however, it is also formed by kansei information such as impression of appearance. The application of the affective interface makes it possible to prevent from accidents or cost increase caused by overconfidence or unnecessary distrust between human and machine.