To provide a data sharing system to share a database of an on-vehicle terminal by applications by mutually transferring information by plural applications.

The on-board terminal 101 is provided with plural applications and databases, an on-vehicle information library to control the applications and the databases and a radio communication equipment 103 to communicate with an external device, a portable terminal 109 is provided with plural applications, a portable information library to control the applications and the radio communication equipment 103 to communicate with the external device, an external database is fetched through the radio communication equipment 103 by the on-vehicle information library and access is made to plural databases via the on-vehicle information library and the portable information library through the radio communication equipment by each application of the on-vehicle terminal 101 and the portable terminal 109.