1. A data management device comprising: a search condition information nontransitory storage medium storing one or more pieces of search condition information, each piece of the search condition information indicating a search condition; a data retrieval portion retrieving, from a storage medium, when a piece of the search condition information is designated, data satisfying the search condition indicated in the piece of the search condition information; a similar search condition information detector detecting as the search condition, when a new search condition is designated by a user, a piece of the search condition information indicating a similar search condition that is similar to the new search condition; and an organizing portion performing, when the similar search condition information detector detects a piece of the search condition information indicating the similar search condition, at least one of the following organization processes: a first organization process of causing the search condition information nontransitory storage medium to store, as one piece of the search condition information, a piece of information indicating the new search condition, and to delete, from the search condition information nontransitory storage medium, the detected piece of search condition information, and a second organization process of causing the search condition information nontransitory storage medium to store, as one piece of the search condition information, a piece of information indicating a search condition specifying a range, the range being overlap between an extent of the new search condition and an extent of the search condition similar to the new search condition, and to delete, from the search condition information nontransitory storage medium, the detected piece of search condition information.