The purpose of this study was to examine the effects of activities with teaching assistant robots on children’s social competence. The subjects of this study were 38 (five-year-old) children attending a Kindergarten in Gongju, Chungcheongnam-do. The instruments used in this study was An Rari(2005) translated Social Competence and Behavior Evaluation (SCBE) of Lafreniere and Dumas (1995) for the purpose of measuring children’s social competence. To test the research questions, two groups means differences of each item between pre- and post-tests were calculated, and then t-tests were conducted on the increased scores from pre- to post-tests. Results of the study were as follows. First, the average of social competence was higher in the experimental group than that of the control group, and it was shown that there is a statistically significant difference (p< .05) as a result of applying t-test to average score increase on social competence test by each group, subtracting pre-test scores from post-test scores of children in both groups. Second, it was shown that there is no statistically significant difference as a result of applying t-test to average score increase on peer interaction test among the subcategories of social competence. Third, it was shown that there is a statistically significant difference (p< .05) as a result of applying t-test to average score increase on social interaction test with adults among the subcategories of social competence. Moreover, it was indicated that there is a statistically significant difference (p< .05) for both cooperation and autonomy in sub-element of social interaction test with adults among the subcategories of social competence. Moreover, it was indicated that there is a statistically significant difference (p< .05) for both cooperation and autonomy in sub-element of social interaction with adults.