This case study investigates the process of the Hyundai Heavy Industries(HHI) group's conversion to the holding company structure, which occurred over three years between 2016 and 2019. Specifically, this paper analyzes 1) the process of the Hyundai Heavy Industries Co.'s spin-offs; 2) the measures taken to meet the requirement for the holding company structure; 3) the change in corporate governance before and after HHI group's conversion to the holding company structure; 4) the change in holding company structure related to the acquisition of the Daewoo Shipbuilding and Marine Engineering Co.(DSME). The results are summarized as follows. The Hyundai Heavy Industries Co(HHI). was spun off into four companies including the Hyundai Robotics, the Hyundai Construction Equipment, the Hyundai Electric, and HHI in April 2017. Before the spin-off, the HHI group was maintained with a circular cross-holding ownership structure, such as “HHI → Hyundai Samho Heavy Industries → Hyundai Mipo Dockyard → HHI”. After the spin-off, the HHI group was converted to the holding company structure, which consists of the Hyundai Robotics as a holding company and the other companies as subsidiaries. In order to meet the requirement for the holding company structure as stipulated by the Fair Trade Act, the HHI group exploited the share exchange between the holding company and the subsidiaries in the same manner of other business groups converted to the holding company structure. The share exchange also worked to controlling shareholder's advantage. As a result, Chairman Chung could exert full control over all group-affiliated companies by possessing almost 30% of the holding company's stake. However, a change in the holding company structure was unavoidable due to the acquisition of DSME in March 2019. According to the acquisition contract, the HHI group had to establish a sub-holding company together with the KDB Bank, which contributed 55.7% of the DSME's stake. As a result, the Korea Shipbuilding and Offshore Engineering was establish a sub-holding company, which controls shipbuilding companies such as HHI, DSME, Hyundai Samho Heavy Industries, and Hyundai Mipo Dockyard.