5. A text search method of a text search apparatus, the text search apparatus comprising a processor, and a memory which includes (i) a document storage for storing document data that includes multiple categories of character string data, the multiple categories including at least one forward-matching-search target category that is a target of a forward matching search, and (ii) an index information storage for storing N-gram index information that includes the multiple categories of character string data, wherein a beginning mark is added before a beginning character of character string data contained in the at least one forward-matching-search target category, and no beginning mark is added before a beginning character of character string data contained in any remaining category of the multiple categories, the beginning mark indicating the beginning of the character string data, and wherein the text search method is implemented by the processor and comprises: acquiring a search keyword; adding the beginning mark before a beginning character of the acquired search keyword, generating N-gram data based on the search keyword having the beginning mark added, and performing, based on the N-gram index information, the forward matching search on the character string data contained in the at least one forward-matching-search target category; generating N-gram data based on the acquired search keyword without adding the beginning mark before a beginning character of the acquired search keyword, and performing, based on the N-gram index information, a partial matching search on character string data contained in the multiple categories; and outputting a result of the forward matching search and a result of the partial matching search; wherein the document data is dictionary data that includes an entry-word data category and a commentary data category, and the at least one forward-matching-search target category contains the entry word category.
5. A text search method of a text search apparatus, the text search apparatus comprising a processor, and a memory which includes (i) a document storage for storing document data that includes multiple categories of character string data, the multiple categories including at least one forward-matching-search target category that is a target of a forward matching search, and (ii) an index information storage for storing N-gram index information that includes the multiple categories of character string data, wherein a beginning mark is added before a beginning character of character string data contained in the at least one forward-matching-search target category, and no beginning mark is added before a beginning character of character string data contained in any remaining category of the multiple categories, the beginning mark indicating the beginning of the character string data, and wherein the text search method is implemented by the processor and comprises: acquiring a search keyword; adding the beginning mark before a beginning character of the acquired search keyword, generating N-gram data based on the search keyword having the beginning mark added, and performing, based on the N-gram index information, the forward matching search on the character string data contained in the at least one forward-matching-search target category; generating N-gram data based on the acquired search keyword without adding the beginning mark before a beginning character of the acquired search keyword, and performing, based on the N-gram index information, a partial matching search on character string data contained in the multiple categories; and outputting a result of the forward matching search and a result of the partial matching search; wherein the document data is dictionary data that includes an entry-word data category and a commentary data category, and the at least one forward-matching-search target category contains the entry word category. 8. The text search method according to claim 5 , wherein in the outputting the search results, an output order for outputting character string data retrieved by the search is determined using an output-order calculating method, and the search results are output in accordance with the determined output order.