Background In Japan, the number of suicides has increased since the coronavirus disease (COVID-19) epidemic. However, only a few studies have examined the trends among individuals who attempted suicide. In this study, we examined the background characteristics and motives of individuals who attempted suicide and visited the emergency room because of suicide-related behavior before and after the spread of COVID-19. Methods This single-center retrospective observational study collected information from electronic medical records. We included patients who presented to the emergency department of Tottori University Hospital with suicide-related behaviors between May 1, 2017, to August 31, 2022. The period from May 1, 2017, through December 31, 2019, was designated as ‘the period before COVID-19” (before-period), and that from January 1, 2020, through August 31, 2022, was designated as “the period after COVID-19” (after-period). We compared the total number of cases, their background, and motives for suicide-related behaviors between the before- and after-periods. Results The total number of suicide events was 304. Of these, 182 and 122 occurred during the before-period and after-period, respectively. The incidence of the F3 category of the International Classification of Diseases, 10th Revision, increased, while that of the F4 and F6 categories decreased during the after-period. The proportion of suicide attempts due to health problems decreased and that of work problems increased during the after-period. Conclusion The total number of suicide-related behaviors decreased after the COVID-19 pandemic. This may be because patients with psychiatric disorders other than depression and schizophrenia often engage in suicidal behavior through non-fatal methods, such as drug overdose and wrist-cutting, which may have led them to refrain from seeing a doctor. The proportion of suicidal motivation due to work-related fatigue has increased, perhaps because the quality and quantity of work changed significantly due to COVID-19.