Recently, many routing protocols and applications for mobile ad hoc networks have been proposed. However, most of them are tested through the simulation experiments, but are not developed and their feasibility is not demonstrated in the real environments. This paper presents a custom selling system in the stadiums as the system using ad hoc networks. This system is used to trade between salesclerks who are selling foods and beverages and customers who are watching the games through mobile terminals for ad hoc networks. We have developed the system and its feasibility is demonstrated at Hiroshima Municipal Baseball Stadium.