The present study examined the recordings of naturally occurring conversations among native speakers of Japanese, and analyzed the cases of iya ‘no’ that are uttered in response to yes-no questions. The analysis has shown that iya can be uttered in response to a yes-no question even when the response to the question is ‘yes,’ as long as the propositional information that follows iya signals ‘yes’ to the question. When iya prefaces a response of ‘yes,’ the speaker can express a stronger message of ‘yes’ since it creates a pragmatic effect of expressing needless to ask… along with signaling ‘yes’ with the propositional information that follows iya.