It has been recognized that prereading activities are important to improve foreign language learners' reading comprehension. This paper focuses on one of the prereading activities for reading comprehension in Japanese, which is regarded to be effective to activate learners' schemata. Using some keywords included in a text, learners infer the content of the text before reading it. The purpose of this study is to clarify the effect of such an activity. The subjects of this study were the Japanese learners of intermediate level, who are studying at the University of the Ryukyus and a private language school. The result does not show statistically significant difference between the control group and the experimental group. However, it was found that the students like the activity. The activity suggest possibility in order to motivate students to read.