The purpose of this research is to reveal that the clothing in a cultural system is a visual symbol expressing the aspects of its technology, social-structure, and ideology. For this, the chilkat blanket of Tlingit is selected and analyzed. Tlingit is the one of the indian tribes of the Northwest Coast of the North America. This chilkat blanket used as an ostentatious item in the potlatch has the various functions. First, it expresses the thechnological features in this society, as the process of weaving, collecting of materials, etc. Second, it provides the view of the social-structure through its role differntiation of sex, and affirmation of the rank systems in this cultural system. And we can see the ideological value of this culture through the chilkat blanket. They persuit the value of labor and the harmony between their lives and the nature in this design. In conclusion, the clothing must be considered and analysed its value in the context of the society.