User innovation, as its definition, refers to innovation by intermediate or consumer users rather than by suppliers, has an extremely wide range of applications in many fields. From the automobile industry to food processing, where there is innovation, we can almost find the existence of user innovation, it has become an indispensable step in the innovation phase of products and services. In this thesis, I will focus on the application of user innovation in the medical field. More precisely, I will discuss how doctors, the users of modern medical equipment, participate in the innovation phase of those various kinds of equipment and affect their development.