The purpose of this study is to classify teachers' scaffolding utterance in Korean language speaking classes and analyze its implementation aspects. Teachers' scaffolding can be classified into four categories according to learners' reaction behaviors. Firstly, when a learner can not respond to teacher's initiation utterance, teachers mainly used the demonstration, providing linguistic clues, providing contextual clues, and restatement strategies. Secondly, when a learner makes an error, teachers mainly used the error correction, meta-linguistic explanation, reformulation, error implication, inducement and encouraging strategies. Thirdly, when a learner appropriately utters, teachers mainly used the acception, expansion, comment, expansion request and praise strategies. Fourthly, when a learner speaks vaguely, teachers mainly used the comprehension check, clarification request and confirmation check strategies. On the other hand, Korean teachers did not use various types of scaffolding, but used specific types of scaffolding intensively. The teachers mainly used the scaffolding in an error correcting category, especially, a reformulation strategy. Although the scaffolding in deepening and expanding category raise the learner's potential developmental level, teachers did not actively use this category.