The purpose of this research is to verify the effect of an Interactive Whiteboard (IWB) for reading in the Japanese class. In this research, the authors compare class A with class B. The teacher can use Interactive Whiteboard in the class A, however she can't in the class B. The teacher and the content of these classes are same. The authors would clarify following research questions. (1) Is the score of class A different form the score of class B in the achievement test? (2) How did the teacher utilize the IWB? (3) How teacher's behavior is observed when she uses the IWB? As a result, the followings are clarified. (1)The score of class A was higher than the score of class B in the achievement test. (2)The teacher utilized the IWB in the situation of "underlining key-sentence", "making the learners write and explain their thought" and "illustrating by a diagram to explain a relation between words." (3)The teacher used the IWB "to make leaners concentrate the subject", "to make leaners concentrate the questions", "to give learners a clue to the solution of the problems", "to make leaners imagine the next activity", and "to connect with leaners' ideas each other." The authors conclude that the IWB is effective in this case in which the teacher have these intentions.