The purpose of this study is to investigate the effects of Somerset Thinking Skills Course(STSC) program on the cognitive change of retarded middle school students. This sudy seeks to test to the following hypotheses. 1)Retarded middle school students, partivipated in the training STSC program will show better improvement in cognitive competence than control group . 2) Retarded middle school students, participated in the training STSC program will show better positive change in the test of Problem Soving Inventory than control group. The sujects were 10 retarded middle school students placing in Pusan, Korea. The subjects in the experimental group reveived the 1st and 2nd module of STSC progam for 43 times. (one time is 45-50 min). To obtain the experimental data, the subjects were pre-posttested on Group Intelligence, Raven\'s Progressive Matrices Test, Representative Stencil Desin TEst(RSDT) and Problem Solving Inventory B form. The results of this study are the following : 1) The statistically significant gain was observed on the measure of Group Intelligence (p<.01), RSDT(p<.05), and Problem Solving Inventry (p<.01) in the experimental group. In addition, positive change in their attitudes were observed. But the result or the test Raves\'s Prograssice Matrces has no significant effects in both group. In conclusion, the result of this study was very positive. Th subjects of experiemtal group who received STSC program improved in both cognitive and problem solving competence.