Korean envoys came to Japan 12 times in the Eto period. They left a number of recorded observations on Japanese society. This article provides an analysis based on these records. Importantly, the Korean envoys hated that Toyotomi Hideyoshi (豐田秀吉) had invaded Korea, especially because of the influence of Confucianism on them. What's more, due to differences in culture, custom and thought between Korea and Japan, their observations on Japanese society exhibited misunderstanding, prejudice and disdain for Japan's wanton customs in a blaze, skeptical character, cruelty, artfulness, etc. However, some of their observations were correct; for example, they are fond of tea, cleanliness, often take a bath, believe in Buddhism, kneel, and abide by the law, etc. In general, the Korean envoys didn't understand Japanese national traits and the distinguishing characteristics of Japanese culture with a tolerant and objective attitude.