This paper considers "masters" as the ideal archetype of workers. Here, the term "master" includes not only those who are in traditional handcrafting or manufacturing industry, but also who work in various fields such as information technology, medicine, arts, and so on. To explore the lifelong learning of masters, we conducted qualitative interviews with 15 masters from various fields. The findings reveal that masters have been through a long and complicated formative circle of learning to become who they are. Specifically, this paper suggests the concept of "masterity (Jang-in-sung, [foreign characters omitted)." Unlike the existing concept of "master craftsmanship (foreign characters omitted)," the term "masterity" accounts for the materialistic and formative aspects of masters' learning. The journey to become a master was a way of developing masterity which was a kind of "habitus" (Bourdieu 2005) of lifelong learning.