To solve the ratio word problems is one of the challenges for children. In the textbook, there are formulas to solve ratio word problems. And students was taught to use formulas when they solve ratio word problems. But the formulas are difficult for children to use (Yoshida & Kawano, 1999). So I focused on drawing diagrams. To solve the word problems, it is effective to draw diagram for children. However, there are few children who try to solve word problems by drawing diagram on their own (Uesaka, 2007). So, I consider diagrams which can be drawn easily for children. In this study, we picked up 3 types of diagrams that we call “line diagram”, “4 squares diagram”, “relation diagram”. 265 sixth-grade students were taught how to draw line diagram, 4 squares diagram, relation diagram. And in post-test, I had students draw 3 types of diagrams for each word problem. The results of the posttest showed that relation diagram is relatively difficult for students to draw and three diagrams equally effective to solve ratio word problems.