This paper is dedicated to the exemplary bilingual text used for study of Japanese in Medieval Korea, the so-called Ch’ŏphae sinŏ (첩해신어 This paper is dedicated to the exemplary bilingual text used for study of Japanese in Medieval Korea, the so-called Ch’ŏphae sinŏ (첩해신어 捷解新語, 1676). These text contains practical expressions and information needed by those Koreans who contacted the Japanese, that is why we focus on it’s rich and historically valuable cultural context to describe the reflection of the diplomatic relationship and state policy of Korea toward foreigners in this textbook: the general impression of the Japanese, Tsushima’s vassal position, Korean attempts to limit contacts, Japanese’ delaying tactic, their complaining, refusing as long as possible to take goods in an attempt to extend their stay in Korea etc.