We report a case study of the interaction of normal and autistic children with Infanoid, an upper-torso humanoid robot. Infanoid is capable of attentive and emotional interaction with humans through gaze, pointing, facial expressions, and so on. In the observational sessions, each of the children sat in front of Infanoid with his or her mother, gradually got into the loop of interaction spontaneously, where he or she played with the robot in a relaxed mood. We assume the relatively high predictability of Infanoid's behavior enabled the autistic child, as well as the normal children, to get into the playful interaction, from which the children could expand the horizon of social communications. This study suggests potential applicability of humanoids to remedial services as well as psychological investigation.