The present invention provides an apparatus for expanding a query requirement, comprising: a query requirement understanding device which generates an explicit query requirement according to a user query request; and a query requirement expanding device which generates an implicit query requirement associated with the explicit query requirement. The query requirement understanding device generates an explicit query requirement including a query concept and a question type by searching a knowledge base and a language base, and the query requirement expanding device generates an implicit query requirement including a query concept and a question type by searching the knowledge base, the language base and a relevancy database. The present invention further provides a method for expanding a query requirement. The apparatus and method for expanding a query requirement according to the present invention can facilitate a user's query and provide the user with an accurate, comprehensive query answer.