Although a tautological sentence does not give us any literal information, it normally conveys some meaning. This study investigated the acceptability and figurativeness of Japanese nominal tautology in terms of the repeated nouns within it and its overall context. One hundred subjects were asked to read five or six different nominal tautologies and (1) to write down situations considered appropriate for each of the tautologies, (2) to paraphrase them, and (3) to rate figurativeness of both the utterance and its paraphrase with respect to the situation imagined. The results showed that the tautologies composed of concrete nouns which have socially evaluated referents (e.g., houseki [jewel] wa [is] houseki [jewel] dearu.) tended to be considered more acceptable than those composed of abstract nouns which have neutral referents (e.g., gen-in [cause] wa [is] gen-in [cause] dearu.), and that tautology was highly acceptable when the context included words whose meanings were opposed to the meanings of the repeated nouns. These findings suggest that tautologies are more easily understood within a context which causes a negative, rather than positive or neutral, evaluation of referents of the repeated nouns.