The purpose of this research is to clarify the way of the treatment of Sakumon in "life-centered arithmetic" in the early part of the Showa era. We pay attention to the arithmetic education on which Iwashita, Fujiwara and Inatsugu insist. They play a central role in the practice of "life-centered arithmetic". Through consideration, we find the following facts. (1) The chief aim of arithmetic education by Iwashita is to develop the qualitative thinking. To realize this aim, he introduces the practice to develop the qualitative thinking in daily life. For instance, gathering the qualitative facts, measurement are examples of this activity. Children pose the problem by the use of these facts or the result of measurement. Sakumon is a part of the practice to develop childeren's qualitative attitude in daily life. (2) Fujiwara restricts the position of Sakumon in his arithmetic education with the reflections that arithmetic education based on Sakumon is not able to preparete the curriculum. He changes Sakumon's position into one of methods of teaching arithmetic, namely the representation of the qualitative life. (3) Inatsugu attemptes to accord logicism with psychologism in arithmetic education. Generalization and specialization of mathematical thinking are the scaffold to accord them. Sakumon becomes the teaching and learning method to cultivate specialization. Simizu's study of curriculum development based on Sakumon has an attraction for him.