This study is a qualitative case study on the meaning of Formal Education in the Lives of Adult Learner students. For the purpose of the study, the five adult learners are selected as cases who had discontinued the formal education in the school years but take the outstanding achievement at their own vocational arena. The research data has been collected mainly by the in-depth interview with the related documents. As the results of this research, adult learners have experienced the following sequential phases: the involuntary \'interruption\' of schooling, the \'pioneering\' of alternative course of learning for survival, the ‘dissonance’ between the visible certification and invisible potential competences. After that, learners tried to return to the site of formal education for gaining a degree. In this process, the meaning of formal education for the adult learners has changed sequentially as the followings: 1) \'the lost prestige\' 2) \'an strange outer world\' 3) \'an unbreakable barrier\' 4) \'a visible label\' and 5)\'a kind of learning resources\'. From the research, there are some implications for the promoting policy of lifelong learning. 1) We need to set up the connection mechanism between the formal education and nonformal education system. 2) We have to introduce the accreditation system of self-directed informal learning.