1. A dictionary registration apparatus comprising: a first storing unit that 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; a first input unit that receives an input text in the first language; an extracting unit that extracts, when the 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 second input unit that receives a similar text that expresses the unregistered text with a different text; a translating unit that translates the similar text into the second language; and a registering unit that registers the unregistered text in association with the similar text translated into the second language on the dictionary information.