Purpose: This study examined the reciprocal relationships between depression and income, and gender differences in these relationships among older adults in South Korea. Methods: Using 2015 to 2019 of the Korea Welfare Panel Study (KoWePS), we studied 6,070 older adults (2,394 men and 3,676 women) aged 60 years over in 2015. The generalized estimating equation was employed to explore the effect of an individual income on depression and the reverse causal link-that of depression on income. Results: The study found the reciprocal relationships between income and depression. Income has a significant impact on depression. Higher-income was linked to decreased risks of the Center for Epidemiologic Studies Depression (CES-D) scores among older adults (B = - 0.121, p < 0.001). Estimates of the reverse causal link show that higher CES-D scores were also linked to income reduction among Korean older adults (B = - 0.007, p < 0.001). In addition, we also observed gender differences in the impact of income on depression but not in the reverse causal link. Income has more detrimental to psychological consequence for older men (B = - 0.108, p < 0.001) than older women (B = - 0.057, p < 0.001). Conclusion: The finding implies that both psychological and social protection policies for the elderly are needed in view of gender perspective.