To reduce an information quantity to be incorporated in an on-vehicle machine and an information quantity to be transmitted between the on-vehicle machine and a roadside machine in an information processing system for providing services respectively corresponding to each vehicle by using radio communication between the on-vehicle machine and the roadside machine.

The on-vehicle machine 10 receiving an inquiry signal from the roadside machine 20 sends an answer signal consisting of identification information and special information back to the roadside machine 20. The roadside machine 20 transmits a retrieving request consisting of an identification signal from the on-vehicle machine 10 and the positional information of the roadside machine 20 to a database server(DBS) 30. The DBS 30 obtains information characteristic to each vehicle from a characteristic information table based on the identification information from the roadside machine 20, selects a service based on this characteristic information and the positional information from the roadside machine 20 and sends information required for providing the service to the roadside machine 20. The roadside machine 20 provides the service to the on-vehicle machine 10 based on the information from the DBS.