A storing unit stores therein dictionary information in which a first text in a first language is associated with a second text that is a translation of the first text into a second language. An extracting unit extracts, when an input text includes an unregistered text that is not registered as the first text in the dictionary information, the unregistered text from the input text. A translating unit translates an input similar text that expresses the unregistered text with a different text, into the second language. A registering unit registers the unregistered text in association with translated similar text on the dictionary information.