Robot therapy for elderly residents in a care house has been conducted since June 2005. Two therapeutic robots were introduced into a care facility, and activated for over 9 h each day to interact with the residents. This paper presents the results of the first month of this experiment. To investigate the psychological and social effects of the robots, each subject was interviewed, and their social network was analyzed. In addition, the activities of the residents in public areas were recorded by video cameras during daytime hours (8:30-18:00). For physiological analysis, residents' urine was obtained and analyzed for hormones 17-ketosteroid sulfate and 17-hydroxycorticosteroids. The experimental protocol was reviewed and approved by the ethical committee of the National Institute of Advanced Industrial Science and Technology. The results indicate that interaction with the seal robots increased their social interaction. Furthermore, the urinary tests showed that the reactions of the subjects' vital organs to stress improved after the introduction of the robots.