1. A device information providing system comprising: hardware comprising: a search request receiving unit that receives, as a search request for searching for a device, a search request including an output requirement for specifying a desired output result; a processing module database (DB) in which information concerning a processing module that receives, as inputs, outputs from one or a plurality of other devices and combines the inputs to generate a new output is registered with respect to a plurality of the processing modules together with at least an input requirement for specifying an input of a processing module and an output requirement for specifying an output of the processing module; a device database (DB) in which information concerning the device is registered with respect to a plurality of the devices together with at least an output requirement for specifying an output of the device; a processing module extracting unit that compares the output requirement included in the search request and output requirements of the processing modules, thereby extracting, from the processing module DB, a processing module capable of acquiring the desired output result designated by the search request; a virtual device generating unit that compares an input requirement of the extracted processing module and output requirements of the devices, thereby extracting, from the device DB, one or a plurality of devices having an output usable as an input to the extracted processing module and generates a virtual device composed of a combination of the extracted one or plurality of devices and the extracted processing module; and a device information providing unit that provides a user with, as a search result, information concerning the virtual device generated by the virtual device generating unit.