To provide a processing system that enables a plurality of processing servers to execute processing in a logically consistent manner without causing overlap or omission upon processing requests from a plurality of clients, and to provide an arbitration server for use therein.

The processing system includes an acceptance server 30 which accepts processing requests from a plurality of clients 20 requesting processing and which arranges the requests in order of acceptance; a plurality of processing servers 50A, 50B-50N which execute processing related to the processing requests accepted by the acceptance server 30; and the arbitration server 40 which, in response to requests from the plurality of processing servers to register the processing executed by the processing servers, accepts the registration of the processing while preventing the double registration of the same processing, and which monitors the execution of the registered processing by the processing servers requesting the registration accepted and cancels the registration in the event that the execution is suspended, thereby arbitrating the execution of the processing by the plurality of processing servers.