Background: The purpose of this study is to analyze the factors affecting the unmet healthcare needs of older people with chronic diseases in Korea and provide a basic research report to strengthen their access to medical care. Methods: In the 2020 older people survey data, 8,182 older people aged 65 or older who were diagnosed with one or more chronic diseases were the final subjects of the study. According to Andersen’s behavioral model used in unmet healthcare needs, independent variables were composed of predisposing factors, possible factors, and necessary factors, and whether or not unmet healthcare needs was set as dependent variable. Results: Of the older people with chronic diseases, 1.6% experienced unmet healthcare needs, of which 55.9% experienced unmet healthcare needs for reasons related to economic burden, 31.6% physical constraints, and 12.5% time constraints. As a result of the analysis, older people with chronic diseases were more likely to experience unmet healthcare needs if they were relatively low in age, low in education level, no spouse, low in household income, poor subjective health, complex chronic diseases, and functional restrictions. However, by major reasons for experiencing unmet healthcare needs, living in rural areas were more likely to experience unmet healthcare needs due to physical constraints, and those who participated in economic activities and who had were more likely to experience unmet healthcare needs due to time burden. These results were not derived when only unmet healthcare needs was set as the dependent variable. Conclusion This study emphasizes the need for an approach by cause of unmet medical occurrence by suggesting that there are differences in influencing factors by reason for experiencing unmet healthcare needs.