Background: From January 2018, a policy was applied to differentially apply the co-payment for medical expenses of 15,000 won or more from 30% to 10%-30% for each medical fee. This policy lowers the burden on the medical use of the elderly, and it is necessary to analyze the effect of the policy by confirming changes in medical use and supply behavior after 2 years. Methods: The National Health Insurance Service’s national medical use database was used. As for the analysis method, first, the medical use and medical supply behavior change over the age of 65 years were confirmed, and second, in order to check the net effect of the policy, the 66-year-old as the experimental group and the 63-year-old as the control group were selected as the control group. The propensity score matching was performed using the variables of age, living alone, income quartile, residence, disability, chronic disease, and co-morbid disease scores, and then it was analyzed using the difference in difference analysis method. Results: The share of the number of treatments under 15,000 won decreased from 37.0% in 2017 to 20.2% in 2018, while the share of the number of treatments under 15,001-20,000 won increased from 8.0% to 22.7%. It was confirmed that the reason for the increase in the cost of treatment per treatment was the result of the increase in the amount of physical therapy and examination. As a result of the policy effect, the burden of co-payment per person was reduced, and as a result, the number of hospital visits per person and the total medical cost per person increased. Conclusion: The self-pay rate differential policy reduced the burden of medical expenses for the elderly and confirmed the increase in medical use. However, the interpretation of the increase in medical use was not able to distinguish whether the unsatisfactory medical care was satisfied or the inducement demand. Efficient allocation of resources is a more important point in the future when the super-aged society is in front. It is necessary to prepare a plan to induce rational medical use within a range that does not impair the medical accessibility of the elderly.