Background: Many people are still infected with coronavirus disease 2019 (COVID-19), and the use of home test kits for diagnosis is becoming common. The misuse of the kits may cause unexpected patient harm. Purpose: The purpose of this case study was to report a rare case of facial skin necrosis caused by contact with a reagent in a COVID-19 Ag home test kit due to misuse of the kit. Case Study: A 50-year-old male patient with pain, redness, and swelling throughout the nose, right ocular area, and forehead visited the emergency room of the hospital. The symptoms were caused by using a COVID-19 Ag home test kit in the wrong way. Initially, partial skin color change and ulcerative skin lesions with pus-like discharge were observed throughout the wound. Finally, partial skin necrosis progressed and was treated using appropriate dressing treatment, antibiotics, and steroids. Conclusion: The use of COVID-19 Ag home test kits that can be easily used will gradually increase. As in this case, it should be kept in mind that problems due to incorrect use of COVID-19 Ag home test kits can occur, and initial treatment is important to prevent systemic infection or scar formation.