Purpose: Psychological distress and related factors in suicide prevention supporters during the COVID-19 pandemic were clarified. Methods: A web-based survey for supporters from helplines or psychiatric institutions was conducted from May to July 2021. It included items about profession, stress and anxiety, and the Kessler Psychological Distress Scale. Results: 818 participants were analyzed. Psychological distress was significantly higher among healthcare workers in psychiatric institutions than among helpline volunteers. The factor most related to psychological distress in both professions was insufficient rest with overwork. Distress in helpline volunteers was related to their lack of ability to support people with suicidal thoughts and suicide attempts, excessive media coverage related to COVID-19, and trouble dealing with complainers. Distress in healthcare workers was related to their lack of ability to provide sufficient support to their clients due to infection prevention measures. Conclusion: Psychological distress among suicide prevention supporters during the pandemic has been affected by overwork, the fact that helpline volunteers cannot be trained in suicide prevention, and the fact that healthcare workers can only provide insufficient support to their clients due to infection prevention measures. To maintain suicide prevention during pandemics, it is necessary to implement measures that are tailored to the factors of psychological distress in supporters.