In this study, we estimate the elasticity of the marginal utility of income using nationally representative household survey data from South Korea, following the direct measurement approach of Layard et al. (2008). Our findings suggest that the income elasticity of marginal utility for the broader population is 1.49 and remains stable over time. Moreover, we explore potential heterogeneity in the income elasticity of marginal utility among individuals. Statistically significant differences in this elasticity are observed across subgroups defined by various demographic and socioeconomic characteristics, including age, marital status, employment status, health status, educational attainment, and net asset positions.