This paper is a practical report on vocabulary learning through a dictionary-making process for students' own interesting things. The class opened for exchange students to learn Japanese language deeply touching its culture and society. Through authentic Japanese, they can improve their skills gathering more vocabulary and expressions and enrich their Japanese world view. Making dictionaries with their own words seemed effective. As another expectation, they can feel achievement by finished task which boosts autonomous learning. The questionnaire after the class showed that it was evaluated with "satisfaction" and "self-learning improving". Practical lessons using the dictionaries have been expected.