Background: The aim of this study was to assess the mental state of Poles in the first weeks of the SARS-COV-2 epidemic. Methods: In the study, the General Health Questionnaire-28 (GHQ-18), The Perceived Stress Scale (PSS-10), and Mini-Cope were used. Results: The study was conducted on a group of 443 individuals, including 348 women (78.6%) and 95 men (21.4%). There were more women (χ2 = 6.42, p = 0.02) in the group of people with high results in the GHQ-28 questionnaire and the differentiating factors between those with sten scores above 7 (significantly deteriorated mental health) and those with average or low results (sten score below 7) turned out to be: treatment for mental disorders before the pandemic (χ2 = 19.57, p < 0.001) and the use of psychotherapy during the pandemic (χ2 = 4.21, p = 0.04) and psychiatric pharmacotherapy (χ2 = 8.31, p = 0.01). The presence of suicidal thoughts since the appearance of the pandemic-related restraints and limitations significantly differentiates the compared groups (χ2 = 38.48, p < 0.001). Conclusions: Every fourth person in the examined group (over 26% of the respondents) recorded results that indicate a high probability of mental functioning disorders. Approximately 10% of the respondents signalled the occurrence of suicidal thoughts since the beginning of the pandemic. The respondents complain mainly about problems in everyday life, lack of satisfaction from one’s own activities, tension, trouble sleeping, and feelings of exhaustion. Individuals with significantly reduced mental well-being use non-adaptive coping strategies, such as denying problems, emotional discharge, taking substances, discontinuation of action, and blaming themselves for the situation. The risk factors for the deterioration of the mental state of the respondents during the pandemic include psychiatric treatment before the beginning of the pandemic, the presence of suicidal thoughts during forced isolation, and the use of non-adaptive coping strategies (denial of the existence of problems, emotional discharge, use of psychoactive substances, discontinuation of action, and blaming oneself for the situation).