Purpose: This study investigated the incidence of urinary tract infection (UTI) in community-dwelling adults and identified the association between obesity and UTI. Methods: The participants were 4,926 adults aged over 40 years who had no UTIs at the baseline survey of the Korean Genome Epidemiology Study. Obesity was defined according to the cirtieria of Korean Society for the Study of Obesity using body mass index (BMI) data. UTI was defined as those who had self-reported UTI or had either nitrite, or both leukocytes and blood in the urine dipstick test. Hazard ratio (HR) and 95% confidence interval (CI) were calculated using a multivariate Cox proportional hazards regression analysis to identify the association between the obesity and UTI. Results: The incidence proportion of UTI was 5.1%, and the incidence density per 1,000 person-years was 25.5. After controlling general characteristics, people with BMI ≥30.0 kg/m2 remained 1.66 times (HR = 1.66, 95% CI = 1.06~2.60; p < .05) more likely to have UTI than those with normal weight. This trend was also present in men or people aged ≥ 60 years. Among women aged ≥ 60 years, people with BMI ≥ 30.0 kg/m2 were 1.98 times (HR = 1.98, 95% CI = 1.01~3.86; p < .05) more likely to have UTI than those with normal weight. Conclusion: The BMI ≥ 30.0 kg/m2 is a risk factor of UTIs in Korean adult men over 40 years and women aged ≥ 60 years. It is necessary to emphasize the importance of obesity management to men or women aged ≥ 60 years, specifically.