1. An information processing system comprising: a request storing section which stores a processing request including description of a plurality of processed devices which are processing objects and description of processing content to be performed thereon; a plurality of processing units which share and execute the processing request; and a plurality of request dividing units which take out an unexecuted processing request from the request storing section when performing the processing request, and divide the unexecuted processing request into a plurality of processing requests, one of which includes description of processed devices of a number commensurate with processing capacity of a processing unit and description of a processing content to be performed thereon, wherein the plurality of processing units are in one-to-one correspondence to the plurality of request dividing units, and from among the processing requests divided by a request dividing unit, a processing unit shares a number of processed devices that is described in the divided processing requests and commensurate with processing capacity of the processing unit, and executes the divided processing requests.