This study examined the developmental process of the request-rejection in communication from the stage before the emergence of speech to the using of speech. My son Yukichi (Y.) was observed at home and his detailed dairy records were kept by his mother from his birth to 30 months of age, and 2700 cards concerning his development were analyzed. 1. The development of the media used for request-rejection When the communicative media used for a specific situation (e. g. feeding) were picked up, the following could be identified: crying→direct behavior (e. g. crawling away, sweeping hand movement) →gesture (e. g. head shaking)→speech (e. g. naei, naei meaning ‘No’). The earlier media did not decrease the significance of communication or were not replaced with the later media but were freely combined. The most complex combination occurred from 14 to 20 months of his age, and in this period, speech was no more than one of the various media. Following that period, speech began to play the most dominant role in his dairylife. 2. The relation between request-rejection and emergence of self-others differentiation By the end of the first year, Y. could use different media properly toward any person in his family, and at 14 months, he behaved himself like a rival as well as a playmate to his sister. At this stage, the acknowledgement of his “Tsumori (image of inten tion or plan)” began to take over the giving effect to his request. The emergence of emotion-cognition such as feelings of rivalry or co-operation with his sister seemed to be based on his differentiation of self-others and the beginning of “Tsumori”.