This study examined the effects of financial performance on the relative firm values of the five banks each in Indonesia and Korea by conducting a comparison, causal relationship, and moderating effect analysis. The financial performances in this research are return on equity (ROE), net interest margin (NIM), Loan to Deposit (LDR), Total Assets turnover (TATO), and assets to equity (A/E). Price earning ratio (PER) is used to represent the relative firm value. Interest rates are set to test the moderating effect on the causal relationship between financial performances and firm values. This study selected five banks each as the sample from the population of the Banks in the Indonesian and Korean stock exchange, Fourty figures were collected for the past eight years, from 2014 to 2021. The analytical techniques are descriptive statistical analysis, independent sample t-test, hierarchical regression analysis, classical assumption test, and significance test. For processing the data, SPSS version 26 is used. The results showed that ROE and NIM significantly affect PER in both countries (NIM: t=2.711, p=0.011; ROE: t=2.192, p=0.036). LDR, TATO, and A/E do not significantly affect PER in both countries. Interest rates marginally moderate the effect of LDR on PER in Indonesia. Interest rates have no moderating effect on the relationship between financial performance and relative firm values in Korea. In the research, ROE and NIM dropped in the Indonesian group, but ROE decreased more dramatically. That implicates that ROE affected the increasing PER level. Meanwhile, NIM dropped, but ROE dramatically inclined in Korea. That affected the decreasing PER level.