This article aims to clarify the difference of meaning expressed by a rising and a falling intonation in the case of the answer particle "okay" in German. Through the method of conversational analysis, "okay" with the rising intonation is compared with that with the falling intonation according to the situation and intention of the speaker. In addition, a comparison with scripted conversations in movies will reveal where naturalness of speech comes from. In the telephone conversation, the falling intonation is used more often. The speaker uses the rising intonation when he leads the conversation and puts emphasis on the intention of the speaker, and the falling intonation when the hearer leads the conversation and puts emphasis on the intention of the hearer. However, in the movie conversation, the rising intonation is used more often. While actors use the intonation in much the same way as in the telephone conversation, there are some exceptional cases. In the movie conversation, the rising intonation is used when the speaker is enthusiastic for the content of the conversation, and the falling intonation is used when the speaker is not enthusiastic. Consequently, the speaker conveys his intention by the difference of the intonation. Producers of movies let actors say lines to express their opinions. In the movie, they use "okay" to claim their opinions, and in the telephone conversation, we use "okay" to communicate with others. Namely, movie conversations are influenced more by the sentiment of the speaker. This difference leads to unnatural speeches found in movies.