[出版社版] ; The purpose of this study is developing a teaching strategy that improves students’ critical thinking abilities and verifying the effects of it. In this strategy, four components of critical thinking abilities are divided between four students as a role and let students discuss about a hypothesis. These roles are rotated in each class repeatedly. Students were divided into two groups; a controlled group and an experimental group. The former was made to discuss without any systematic roles. The latter was made to discuss with own role. As a result, there were more students who could acquire the critical thinking abilities in the experimental group. There were more utterances related to the critical thinking abilities in the experimental group and the more students practice their roles, the more utterances could be seen. What is more, the experimental group’s score of the test, which examine whether students could acquire these abilities, is higher than controlled group. According to these results, it is suggested that this strategy is useful to improve students’ critical thinking.