Functionality is not the only major objective of service robots design, but safety and affinity are also necessary. This study focuses on a design policy for a service robot that can be used to transport people in a real world environment. In this paper, a design policy which referred to the rules of a real world robot challenge (RWRC) called "Tsukuba Challenge 2010" and an idea to design the robot's body which is suitable for navigation method based on internal sensors, are presented. The design policy emphasizes functionality, safety, and affinity. Therefore, a service robot which can ensure the functionality and the safety during coexistence with humans can be developed. In 2010, we developed a robot with affinity and applied it in many events including Tsukuba Challenge. A questionnaire on the robot's perfection level was taken during the events. Feasibility of the proposed policy is shown by the results and performance of the demonstrations.