Abstract
Epidemiological research which focused on impacts of the COVID-19 pandemic on mental health have been conducted worldwide. This article aimed to: 1) review relevant research articles to identify both risk and protective factors of negative impacts caused by the pandemic, 2) to identify still needed information, and finally 3) to propose particular types of research necessary for the future. A variety of demographic variables as well as psycho-social factors were found to be risk factors or protective factors. It has not been clarified whether these factors interdependently function when the COVID-19 outbreak negatively impacts an individual’s mental health. In addition, only presumable factors have been examined as to whether they are risk or protective factors. Compared to epidemiological studies targeting a relatively large sample, there were few clinical case studies which described the psycho-social process leading to an individual’s maladaptation. In order for these issues to be solved, the author proposed a few essentials in conducting future research.