Objectives: The recent novel coronavirus disease (COVID-19) pandemic has led to restrictions in physical activity. We evaluated the impact of risk perception on physical activity, and its impact on kidney function in chronic kidney disease (CKD) patients during the pandemic. Methods: A population of CKD patients registered in a SKETCH (Study on Kidney disease and EnvironmenTal Chemicals, Clinical Trial No. NCT04679168) cohort recruited from June 2020 to October 2020 was included in the study. Patients were followed-up every 3 months for a year. We obtained risk perception and physical activity information by a questionnaire survey. Physical exercise, 3-times/week, was categorized into three groups according to the frequency of positive response during 5 visits: group 1, 0-2; group 2, 3-4; group 3, 5. We used Logistic regression analysis to identify the significance of risk perception to physical activity. The cox-proportional hazard model was used to identify the significance of physical activity for kidney function. Results: A total of 262 patients were included, and the mean age was 60.5±12.8 years old. Mean eGFR was 43.4±20.9 mL/min/1.73 m2, and there were 220 (84.0%) with eGFR <60 mL/min/1.73 m2. There were 122 (46.6%) of patients who showed higher risk perception for COVID-19 infection. After adjustment with age, sex, comorbidities, and laboratory results, higher risk perception was significantly associated with decreased physical activity (adjusted OR 0.44, 95% CI, 0.23, 0.84). During 364.8±38.6 days, 52 (19.8%) patients showed decreased kidney function with decreasing eGFR ≥30%. Group 1 showed a significantly increased risk for kidney dysfunction (adjusted HR 3.36, 95% CI 1.23, 9.20). This result was prominent in age over 60, male sex, patients with hypertension. Conclusions: Decreased physical activity related to higher risk-perception, and that was significantly increased risk for kidney dysfunction. Healthcare provider needs to consider a new strategy to encourage physical activity irrespective of risk perception.