Background: Pandemic of coronavirus disease-2019 (COVID-19) puts a heavy burden not only on patients physical and mental health but also on regional health care resource and economic activity across the world. Although we accumulate incidence rate and case fatality rate by the multidisciplinary approach, epidemiological data of prevalence of serum severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) antibody in health-care workers during COVID-19 peri-pandemic period is insufficient. Methods: We prospectively recruited health-care workers from our hospital between April 10 and April 20, 2020. We collected serum samples from these participants and evaluated quantitative SARS-CoV-2 IgG antibody by enzyme-linked immunosorbent assay. Results: Five (5.4%), 15 (16.3%) and 72 (78.3%) participants showed positive, borderline and negative results of the serum SARS-CoV-2 IgG antibody, respectively. We found mean titer of the antibody levels of all, positive group, borderline group and negative group were clearly distinguished. Participants belonging to otolaryngology ward and/or having a history of seasonal common cold symptoms had significantly higher titer of SARS-CoV-2 IgG antibody (p=0.046, p=0.046, respectively). Conclusions: Five (5.4%) and 15 (16.3%) participants showed positive and borderline SARS-CoV-2 IgG antibody during COVID-19 peri-pandemic period. These rates were much higher than the rates expected from situation reports of the government. Higher rates of positive and borderline antibody suggested that COVID-19 had already spread at early stage of pandemic in the southern part of Kyoto city.