Objectives: It is well known that various air pollution factors increase the risk of kidney disease. We aimed to elucidate the risk of chronic kidney disease according to the indoor and ambient particulate matter 2.5 (PM2.5). Methods: The kidney function and the ratio of indoor and ambient PM2.5 was extracted from the Korea National Health and Nutrition Examination Survey (KNHANES) VIII (2019─2021) dataset. CKD was defined as estimated glomerular filtration rate (eGFR) less than 60 mL/min/1.73m2, and the association between the indoor and ambient PM2.5 ratio and CKD was analyzed through multiple linear regression model. The indoor and ambient PM2.5 ratio was divided into tertile groups (T1, T2, and T3). Results: The indoor air quality of 1,319 participants was analyzed in this study. The indoor PM2.5 concentration and the ambient PM2.5 concentration did not show a statistically significant association with CKD respectively. However, the highest quartile of indoor and ambient PM2.5 ratio was associated with increased risk of CKD (odds ratio, 4.28; 95% confidence interval, 1.43─12.75, p-value 0.009) after adjustment of age, sex, comorbidities, and window opening status. Conclusions: In this cross-sectional study, the indoor air quality of PM2.5 relative to the concentration of PM2.5 in the ambient air was associated with the deterioration of kidney function.