The concept of citizen science(CS) is defined as "scientific work carried out by citizens." Here, 'citizen' means someone who has knowledge of everyday life, regardless of whether they have formal expertise in a related field. This definition may encompass scientists, as many scientists participate in scientific democracy and use their expertise in a citizen-oriented manner. That work is derived from their citizenship, so their scientific work is CS. CS in Korea has expanded from the Korea Pollution Research Institute, which was founded in 1982, to the Center for Democracy in Science & Technology, which was founded in 1997. Furthermore, in recent years, government agencies have started using CS approach. In this paper, I introduce Korean CS and examine its accomplishments and difficulties through eight cases. I show that Korea's CS activities have made a significant impact on Korean society and the experience of these activities has implications for the future directions of CS. I do so by examining four modes of CS and explore practical messages for more varied roles of CS. Until now CS has been mainly considered in the context of "CS as education" or "CS as movement" in Korea. However, governance and the platform mode of social decision-making or research, though still rare, have recently emerged as additional CS activities. Although it cannot be said with certainty that CS is better, it is undoubtedly better the more varieties of its modes coexist. The four types of CS will contribute individually or complementarily to social learning. Thus, because of its distinctive potential, CS is not exhausted by the supplementary concept of science.