An apparatus for searching similar sentences that has a translation sentence database includes an input unit to which a sentence is input; first language processing unit configured to perform language processing on sentences input through the input unit; and first language similarity calculating unit configured to refer to previously translated sentences to extract similar sentences for the first language sentence. Further, the apparatus includes translating unit configured to translate a sentence into a second language sentence; second language processing unit configured to perform language processing on a second language sentence; second language similarity calculating unit configured to refer to the previously translated sentences to extract similar sentences for the second language sentence; and a re-ranking unit configured to combine similar sentence extracting results of the first language with those of the second language to re-rank sentence outputs.