1. An example-based translation apparatus comprising: a storage unit that stores source examples of a source language and target examples of a target language in a many-to-many relationship meaning that each of the source examples is associated with one or more of the target examples having the same or similar meaning, and each of the target examples is associated with one or more of the source examples having the same or similar meaning; an input receiving unit that receives an input of a sentence in the source language; a source example search unit that searches the storage unit to identify one or more of the source examples based on the sentence in the source language; a target example search unit that, for each of the first source examples, searches the storage unit to identify one or more of the target examples that have similar meanings as the identified first source example: a determining unit that determines whether there are a plurality of identified target examples; a first acquisition unit that, for each of the identified target examples, acquires from the storage unit one or more second source examples that correspond to the identified target example, when there are the plurality of identified target examples; a second acquisition unit that, for each of the second source examples, acquires from the storage unit one or more target examples that correspond to the second source example; a choice generating unit that chooses one of the second source examples that is associated with the fewest number of the acquired target examples; and an output control unit that outputs the chosen second source example.