Lee Haesuk This phenomenological study analyzed the advantages and disad- vantages of online-activity-based instruction experienced by Korean language teachers during the COVID-19 pandemic. For this purpose, Colaizzi’s method was used in analyzing a video clip of a YouTube lec- ture(Mulkko TV). The advantages of online-activity-based instruction in the Korean language class were identified as automatic archiving of ac- tivity data, increased access to activity data, decreased presentation time, focused and intensified thinking, and reduced burdens of writing and presentation. The disadvantages include an unlively mood, lack of teach- ers’ involvement, lack of connection with other classmates, and restricted access to learning materials. While the disadvantages of online-activi- ty-based instruction in Korean language classes are also commonly ob- served in other online classes, it offers greater advantages than in other subjects owing to the nature of the subject of Korean language. This study provides substantial examples of online-activity-based instruction in Korean language classes and provides specific information on their ap- plicability.