1. A method comprising: calculating, by a server computer, a plurality of areas where a mobile body may arrive on a basis of dynamic map information; calculating, by the server computer, for an event occurring in the plurality of areas, an estimated arrival time of the mobile body at a region affected by the event, wherein calculating the estimated arrival time comprises using the dynamic map information on a basis of a distance between the mobile body and the region affected by the event, a speed of the mobile body, flow volume on a road, a number of intersections that exist between a current position of the mobile body and the road, and travelling history information; calculating, by the server computer, for the event occurring in the plurality of areas, an arriving probability of the mobile body arriving at the region affected by the event, wherein calculating the arriving probability comprises using the dynamic map information on a basis of a reliability of the event, connection of the road where the event is occurring, a number of roads where the mobile can choose to travel on at an intersection, the calculated estimated arrival time, and the travelling history information; extracting, by the server computer, an avoidance position for enabling the mobile body to avoid arriving at the region affected by the event; calculating, by the server computer, an encountering probability of the mobile body meeting the region affected by the event on a basis of the reliability of the event, the arriving probability, and the avoidance position, wherein the encountering probability is a percentage; and notifying, by the server computer, the mobile body of the encountering probability, wherein the encountering probability is displayed on a display device associated with the mobile body and wherein the display device displays risk and avoidance information for each traveling direction of the mobile body.