To enable asynchronous reflection between databases without pressing a storage capacity.

A data processing device is provided with a first database 101 in which data is managed with time information at the time of update process including an addition and modification, a second database 102 in which the first database 101 is reflected, and a reflection part 103 which reflects the data managed by the first database 101, comprising the time information of a period from the time of a reflection processing performed immediately before to this reflection processing, in the second database.