A vehicle 2 performs fault diagnosis of the vehicle and calculation of the service life of parts using information obtained from sensors and control units, and when the necessity for repair work of the vehicle arises, makes a repair request to an information center 1. The information center 1 having received the repair request notifies terminals of outlets 4 of the repair request, to request the outlets 4 to transmit a service condition of their shop. The outlets 4 transmit the service conditions of the shop to the information center 1, in response to the repair request. The information center 1 relays the received service condition of each outlet 4 to the user, so that the user can select a desired service condition. The information center 1 then transmits contract completion information to the outlet 4 having proposed the service condition selected by the user, to mediate an agreement between the user and the outlet 4.