This paper proposes a method to automatically organize and visualize related work events as a work-project structure. This is accomplished by accumulating and analyzing the target event and time of the user's operations such as registrations and references on a Personal Information Management system (PIM). Our processes for organization are : (1) extracting relations between events from the records of user's reference operations using balloon-help function, (2) intensifying the relations between events during interaction with the user by visualizing the relations and presenting them to the user, (3) making connections between events based on the extracted relations. Our visualization method represents the organized work events as connected graphs in which nodes and arcs indicate events and relations between events, and in which the intensity of the relation is represented with arcs of width in proportion to the intensity. Furthermore, in order to visualize a structure of collaboration among several users, our visualization method places each user's connected graph on the side planes of a three-dimensional multi-angular prism.