In this study, excellent language learners were defined as Korea-Japan international conference interpreters who have the highest level of communication skills in Japanese language, and, based on analysis of tendencies and learning characteristics related to learning strategies they use for learning Japanese, factors that can influence successful learning of Japanese language were discussed and analyzed. The result shows that. First, international conference interpreters use various learning strategies for learning Japanese language and, particularly, cognitive strategy to understand and use the target language, alternative strategy to supplement insufficient linguistic knowledge, and meta-cognitive strategy to control the learning process. Second, as a factor that influences successful learning of Japanese language, in terms of learning environment, constant learning of and exposure to Japanese language by media, etc., had the most positive effect on the learning result rather than staying in JSL (Japanese as a Second Language) environment.