This study aimed to discover how the stimulus of the noise from a robot affects a child through the interaction between a robot and autistic children. We selected four autistic children and derived the following ideas about the stimulus of the noise from a robot from a review of the literature: (1) The variation of the observation process and operation about the stimulus of the noise from the robot, (2) the children's reactions to the particular stimulus of the noise from the robot, (3) the test shows that children's reaction to the stimulus of the noise from the robot is positive. First, the study found that the noise from the robot could stimulate the children to observe and operate it, and that the children changed their observation process and operation in accordance with their conditions and interests. Second, the children responded in very different ways to the singing function of the robot. Third, our study showed that the sound stimuli from the robot positively affected children labeled with autism in imitation of speech and behavior.