In a document retrieval system for retrieving a document from documents stored in storage devices according to a retrieval condition input by a user, the storage device where a retrieval is carried out is selected from the storage devices, and the retrieval condition is input. In the selected storage device, when the retrieval according to the input retrieval condition is carried out, based on a retrieval result, information indicating the number of documents satisfying the retrieval condition is managed for each storage device where the retrieval is carried out. When the retrieval condition is input, based on the managed information, whether the number of documents stored in any selected storage device and satisfying the input retrieval condition is larger than a predetermined number is determined before carrying out the retrieval. As a result of this determination, control of whether to conduct the retrieval is achieved.