An information processing device creates a dirty bit indicative of an update state for each combination of sharing bags between parties. A database processing section updates the dirty bit of a tip by monitoring any modification to the tip during a non-synchronous period. A synchronous process is carried out between two information processing devices, in which whether it is required to transfer the tip and transfer direction are decided after transfer of the dirty bit. Further, the dirty bit which relates to the synchronous process is updated and the update is transferred to the other dirty bit which corresponds to the tip. As a result, it is possible to reduce communication data volume and to find a coincidence in tips between three or more information processing devices, thereby realizing a database managing device which can reduce communication data volume in the synchronous process in a database system in which associating data can be independently updated by a plurality of devices.