Background: Premature ventricular contractions (PVCs) are often found in healthy workers at medical checkups. In this study, we aimed to investigate the frequency of PVCs recorded during medical checkups in Japanese office workers without heart disease or other known contributing factors. Methods: Participants in this study were 17,641 office workers, who underwent an electrocardiogram examination during a regular medical checkup between April 1 2015 and March 31 2016 and had no known heart disease. The frequency of PVCs was recorded. Participants with PVCs were included in the PVC group and a control group of participants without PVCs was set in a nested case-control study to calculate the rate of complications for lifestyle-related diseases and the risk rate of PVCs for lifestyle-related habits. Results: Within the participant group, PVCs were observed in 303 individuals (1.7%). When compared with the control group, the occurrence of regularly drinking alcohol (P=0.009) and insomnia (P=0.006) were significantly higher in the PVC group. Factors related to the onset of PVCs were examined using univariate analysis. The odds ratio (OR) was 1.731 in participants who regularly drank alcohol (95% CI: 1.146-2.633, P=0.009) when compared with participants who did not regularly drink alcohol, and 1.569 in participants with insomnia (95% CI: 1.023-2.422, P=0.040) when compared with participants without insomnia. Conclusion: The frequency of PVCs recorded at regular medical checkups in Japanese office workers without heart disease was 1.7%. Within our group of participants, the factors related to the onset of PVCs were a history of regularly drinking alcohol and sleep disorders.