Recently, the educational approach called “cognitive counseling” has been proposed as the effective teaching method which applies the knowledge obtained in psychological research to practice in school education. This study is a case report of the cognitive counseling for a boy of sixth grader who has difficulties in understanding of the arithmetic. Our assessment revealed that he may try to learn contents off by heart or may operate them only in his head. Therefore he cannot attain knowledge organization, and that could make him experience difficulties in arithmetic. So we aimed at correcting his inadequate knowledge and helping him acquire appropriate learning strategy by suggesting the learning strategy that utilized external resources. A concrete advice to him was to use the label as more appropriate strategy. As a result of these supports, a part of his inadequate knowledge has changed and became appropriate, and he became able to use labels. It was suggested that he exploited and adopted the learning strategy which use external labels effectively.