Human being represents his emotion through facial expression on purpose or unconsciously. Several psychologists started the research for analysis of facial expression, and over the last decade, many computer scientists were also interested in it. Facial expression recognition is a future-valuable research that can be applicable in many kinds of field based on man-computer interface. However, in spite of lots of study, it is hard to find any practical systems because of a variety of illumination and scale of face, and high dimensional information to be processed. In this paper, I tried to describe a generic framework for facial expression analysis, the need of each level, and international research tendency. Also, I analyzed the case study of facial expression in Korea. I expect it to be helpful for the scientists willing to make contribution on facial expression.