This study examines the effects of job grade simplification, a prevalent form of organizational delayering in Korean firms, on organizational culture. Although job grade simplification is intended to reduce hierarchical rigidity and promote horizontal interaction, empirical evidence regarding its cultural impact remains limited. Drawing on Schein's (1983) three-level model of organizational culture and Blumer's (1986) symbolic interaction theory, this study investigates whether artifact-level institutional change diffuses into deeper cultural layers. Using a mixed-method approach, Study 1 analyzes media discourse through news text analysis and identifies hierarchy reduction and horizontal culture as the primary intended outcomes of job grade simplification. Study 2 employs panel data from the Human Capital Corporate Panel (HCCP) to examine whether these expectations are realized in practice. The results show that job grade simplification has no significant effects on hierarchy-oriented or innovation-oriented organizational culture, and the moderating roles of autonomy and performance-based pay are not supported. Overall, the findings demonstrate that institutional reforms such as job grade simplification do not automatically translate into changes in deep-seated organizational culture. By empirically identifying the gap between institutional change and cultural transformation, this study highlights limitations of delayering as a stand-alone mechanism for cultural change.